A while back, I wrote about why there are no green stars in the sky (you should read that post first; some of the concepts below are explained there).
But that’s not to say there are no green objects in space. There are!
Low-density gas clouds, like NGC 6826 (which I studied for my Masters degree, incidentally), emit light in a very different way than stars do; they aren’t blackbodies at all. They are more like fluorescent lights, giving off lights at very specific colors, and not continuously across the spectrum.
If the cosmic gas is hot, and contains oxygen, the nebula can strongly emit light at about 500 nanometers, smack in the green part of the spectrum. They also emit some red and other colors, but they don’t emit across the entire spectrum like stars do. These objects do in fact look very green through the telescope, but remember, they’re not stars!
The planet Uranus looks green too, but that’s because its upper atmosphere has lots of methane, which absorbs red light. Again, it’s not a star so it doesn’t count.
Now, I do have to say, there is a way for some stars to kinda sorta look green. We sense colors not just on an absolute scale, but also by comparison as well. An object that looks one shade of red by itself will look a different shade if you put it next to a yellow object. Your eyes and brain together can be fooled this way.
Almach is multiple star system in Andromeda (though to the eye it looks like just one star), and its components do just this. The brightest star is an orange giant, a star like the Sun that’s dying. It’s cooler than the Sun, and so looks orange to the eye. The other three stars comprising the Almach system are white dwarfs, dead stars that glow due to their leftover heat. Two of them are barely separable by telescope, and the third orbits one so closely it’s impossible to see. But the combined light of these three stars is whitish… but when you look at it through a telescope, with the orange star visible as well, the trinary takes on an emerald green glow! It’s not real, in that it’s an illusion, but it does still look green. Interestingly, in all the images I found, it looks bluish; maybe the camera is not as easily fooled as our brains. Other examples of multiple stars like this can be found, too.
But is there a star that’s intrinsically green? Zubeneschamali is the second brightest star in the constellation of Libra. It’s somewhat hotter than the Sun, and some people claim it looks green to them, while other say it looks white. It’s unclear why; some people’s sensitivities are different, but it might also have to due with the star itself: Zubeneschamali is a young star and a rapid rotator, which might affect its colors (the emitted light from a star is not really a blackbody, and its youth and rotation might have some influence on its emitted colors).
So maybe, maybe, there is one intrinsically green star, but even then its controversial.
There are several lessons here. One is that stars really can’t be intrinsically green; they need to be seen against a contrasting color to look green, and even then it’s just a trick. Also, there are green objects in space, but they are very different than stars (gas clouds and planets). And finally, the color we see from an object depends on how that object emits light, which can be just as important as the light emitted itself.
August 28th, 2008 at 1:16 pm
That picture creeps me out! It’s either some sort of giant eye looking at me, or a pokemon trying to hug me. Not sure which, but both prospects are frightening to my mental health!
Interesting blog post. By the way, get my email about the pareidolia nonsense on CNN?
August 28th, 2008 at 1:22 pm
Of course there is no speck of gas anywhere in that picture.
August 28th, 2008 at 1:26 pm
Nice post, Phil! However, I have to do some nitpicking. I don’t think that Uranus is really green to the naked eye, but it just appeared that way in the original releases of Voyager 2 images due to processing. Emily recently linked to Don Davis’ page that deals with planetary colors, and it’s very informative (link below).
http://www.donaldedavis.com/2002_addons/SSYCOLRS.html
August 28th, 2008 at 1:31 pm
Speaking of poufy clouds of gas…
August 28th, 2008 at 1:47 pm
Larian:
Close your eyes and take a deep breath. Go ahead…
There.
You just benefited from the work of a planetary nebula like the one in the picture. This is where oxygen comes from. The green glow you see there is from doubly ionized oxygen that is fluorescing under the UV light emitted by the white dwarf you see in the center.
Nathan:
http://en.wikipedia.org/wiki/Doubly_ionized_oxygen
‘Nuff said.
IMHO Uranus is one of the finest sights in the universe (next to Swoopy?). It looks cyan (blue-green) to my eye. Stunning.
Rich
August 28th, 2008 at 1:49 pm
It’s weird. I had to enter that last post twice to get it to appear and when it did it said “Your comment is awaiting moderation.”
What are the rules regarding such automated replies?
Just curious…
Rich
August 28th, 2008 at 2:07 pm
Um.. That picture of the planetary nebula. Is that not one of the HST’s false-color images, where red, green, and blue are due to the brightness of certain lines of elements like hydrogen, oxygen, and nitrogen? (I can’t recall exactly which, but I know that the red is hydrogen.) So it wouldn’t really look green, right? It would look red in a real-color image since hydrogen is the most abundant element in these clouds.
August 28th, 2008 at 2:11 pm
[you just knew someone was going to ask that, didn't you?
]
August 28th, 2008 at 2:23 pm
@PG
According to the discription:
http://www.spacetelescope.org/images/html/opo9738d.html
It’s actually green. Also, someone who got his master’s degree on studying it probably won’t confuse an increased data picture for a normal one
August 28th, 2008 at 2:26 pm
You can see pictures from Almach at Jose Suro’s site. And there is a greenish picture of Zubie at Maxmillian Nikomi’s site.
BTW, I must confess that aside of white Vega and red Antares all the other star look very much the same colour at naked sight.
August 28th, 2008 at 2:55 pm
Is it right to say the brain is fooled? Isn’t it more accurate to sat that all colour is subjective, but that usually (but, crucially, not always) what we perceive as green is light around 500nm. In other words, ‘green’ is defined by our experience, and we have found be experiment that most greens have the same physical explanation. There is no such thing as ‘intrinsic’ greenness, there’s only electromagnetic radiation and eye-brain response.
August 28th, 2008 at 2:55 pm
Psh. I’ve seen plenty of green stars. I colonize the planets around them every time I play Master of Orion.
Uhh…videogames are real, right?
August 28th, 2008 at 3:02 pm
@PG:
You will see some green anyway. As Phil mentioned, one recombination-line of oxygen is roughly at 500nm which is in the green part of the visible spectrum. So, if there is oxygen abundant in the cloud you will see some green….
@Nathan:
You mean that there is a plasma, again, right? I don’t know if you read my posts in the other blog entery, maybe my english is too bad (I’m sorry!)….. But: Of course the “gas” is a plasma, right! But the motions of the particles are NOT aligned, they are random! So there is no current resulting in no electromagnetic field. So the plasma will (on large scales, as we can always (or mostly) asume in astrophysics) behave just like a gas, a hot gas. It is ionised, of course. It has to be! Because would it not be ionised, there would be no recombination and no radiation and we could not see the whole thing (ok, there could be some blackbody radiation but we may leave this out, now).
Hopefully my english was well enaugh that I could made my point clear. Maybe
Btw: We waited a LONG time for that post, Phil
August 28th, 2008 at 3:27 pm
@DrFlimmer: [begin a bit of pedantry] the abundance of Hydrogen is about 10,000 times greater than that of oxygen in these nebulae. So there’s some green (if just a tiny bit). I’m just saying that the green would not be visible if you looked at the object in true color, and all you’d see is the overpowering red of the H-alpha line at 626nm (the HST people have “cranked up” the green to bring out the details in the compositional information). Everything Phil said is right, I just wanted to point out to the general reader that the photo is somewhat misleading (even if they did use HST images like these in Star Trek: Voyager!) [pedantry complete!]
August 28th, 2008 at 3:31 pm
@PG:
The Orion Nebula has always appeared distinctly green to me through both my small refractor and my 8″ reflector. (Size does not seem to matter. Er. Ahem.) It’s considerably different from other bright nebulae, for instance the Lagoon or the Omega, which appear very neutral. At least to my eyes, which are admittedly kind of wonky.
August 28th, 2008 at 3:32 pm
I suppose I could make a lame Green Lantern joke, but that’s beneath even me. Which is my way of saying I can’t think of one, darn it.
August 28th, 2008 at 3:37 pm
FWIW, the planetary nebula NGC 6210 (AKA the Turtle) in Hercules looks unmistakably green in the eyepiece of a telescope, to me anyway.
August 28th, 2008 at 3:50 pm
@PG
It’s not just the relative abundance of hydrogen to oxygen that determines if something looks red or green. The rate of emission (how many photons are emitted per atom per second) which depends on quantum mechanics of that line and things like the temperature and pressure of the gas/plasma and what radiation (usually UV from hot stars) is hitting the gas/plasma. (For example, A-type (white) stars have the strongest visible-light hydrogen lines (dark against the background blackbody), while both hotter stars and cooler stars have weaker or absent lines — not because they have less hydrogen, but because the temperature changes the state of the hydrogen’s electrons.) In fact, for many nebulae, the boundary you see might not be the extent of the gas, but the place where conditions change from where the atoms are in the right state to where they aren’t.
Then you have to consider the human eye (or film, or CCD), which is more sensitive to different parts of the spectrum — I know CCDs show the Orion Nebula as red, while most people who look at it through a small telescope will see it as green.
August 28th, 2008 at 4:14 pm
And, for anyone not convinced that the brain can be “tricked” into the perception of color and brightness, I would point them to this web page:
http://web.mit.edu/persci/people/adelson/checkershadow_illusion.html
August 28th, 2008 at 5:19 pm
PUNY HUMANS, MORBO IS A NEWS ANCHORMONSTER OF STELLAR PROPORTIONS!
>_>
Aaaaanyway. I was also wondering about whether the image is a true-color one. I think we’re so used to the Hubble palette that we forget about it sometimes.
It doesn’t say either way in the image info:
The WFPC2 is the same instrument that took the famous false-color image of the Pillars of Creation in the Eagle Nebula, so it can do either, apparently.
August 28th, 2008 at 5:24 pm
@DrFlimmer: “But the motions of the particles are NOT aligned, they are random! So there is no current resulting in no electromagnetic field.” That’s an assumption, based on no evidence and no reason beyond that it might be inconvenient if it weren’t so. There’s no honest reason not to just call it what it is, but plenty of dishonest reasons.
“Oh, look, the whole city of New Orleans is under ‘hot ice’!”
August 28th, 2008 at 5:42 pm
The human eye is not very sensitive at all to H-alpha emissions at 656.3 nm, and is much more sensitive to O-III emission at 500.7 nm. So even if more H-a light is produced, the human eye may see the green colour more clearly. Hydrogen may also produce H-beta emissions at 486 nm, adding a blue-green colour.
August 28th, 2008 at 6:28 pm
Larian LeQuella Says:
“That picture creeps me out! It’s either some sort of giant eye looking at me,”
Sauron Lives!!!
Great Picture
August 28th, 2008 at 7:34 pm
stars that are red, blue, with pink polka dots…who cares…pretty pictures
August 28th, 2008 at 11:02 pm
Ha, it kind of reminds me of the sanity guardian from Eternal Darkness. Pareidolia are great.
Keep up the hard science articles Phil, the earth needs as many good science writers as we can get.
Off topic, but where is your email address listed? I can’t find it anywhere on the site and I have a couple of questions for you if they’re not too much trouble. Just email it to the address I put in to post this or post directions to the right part of the site in this thread. Thanks.
August 29th, 2008 at 1:25 am
When I read the first thread, which disclaimed green stars, I wondered about human color blindness and the other condition. The other condition makes it difficult to read numbers of one color in a plate of dots of mixed colors.
Wouldn’t a color id disfunction cause that person to see a green star?
About M52. I’ve viewed it through 6×30 and 10×50 binocular; and through both my 60mm refractor and 8″ reflector (all gone, but the 6×30 binocular).
Everytime I looked at the Orion Nebula, it looked white, to me. I’m always facinated by the Trapezium constellation in the nebula. I could get to be a deep space observer, if I don’t watch myself. smile
When I get caught up with some bills, my next set up (binocular, adaptor and camera tripod) will be with a 12×60 binocular; and my next ’scope will be an 80mm short tube refractor. But, that waits, until I get bars on my windows. I have no plans for another medium reflector.
August 29th, 2008 at 1:44 am
Totally off topic, but I thought you might enjoy this:
http://amorphia-apparel.com/design/darkenergy/
August 29th, 2008 at 2:04 am
@Don: The most common color blindness makes red and green indistinguishable. A red star would thus look “red or green, who knows?”. It’s not really the same, though, is it?
August 29th, 2008 at 3:11 am
@Nathan Myers
Quite right. That is exactly what my son has, colour vision deficiency, and “who knows” is exactly his response to any red/green question. He never knows if we are watching grass court tennis from Wimbledon or clay court tennis from Roland-Garros!
August 29th, 2008 at 4:00 am
Madge, if a European, probably a Spaniard, is winning it is Roland-Garros. If a yank or an aussie is winning it is probably Wimbledon.
August 29th, 2008 at 4:12 am
@Nathan:
Well, that gave me a smile
(”hot ice”)…. In some way you are right. Why not call it a plasma, when it is one… but there are some things I want to add:
One: astronomers are a “wierd species”, because they call everything as they want. Heard an astronomer use the word “metal”? Do you know what he means? Not only iron and copper. He means EVERY element which is heavier than helium, so he also means oxygen, carbon, neon, and so on. These are elements normally not known to be “metals” – but astronomers call them that way.
Two: I count on thermodynamics. Temperature has something to do with the kinetic energy of particles (or with the speed of them). And the speed (and I don’t say velocity here because the motions are NORMALY not aligned and thus have no “overall” direction) is distributed like a Maxwell-distribution – but, again, not aligned. This works for all the air around you, I guess you will agree with me here.
Now the plasma: Take an interstellar gas-cloud (intergalactic gas-cloud is also possible). It won’t be very warm unless there is something to heat it. If it’s heated then the particles will start to “move” randomly according to the laws of thermodynamics, and, if the (heat)radiation is energetic enaugh, the atoms will be inoniesed according to quantummechanics. So, we gain a plasma with partcles moving randomly, right?
So now electrodynamics: A current (especially a changing one) induces a magnetic field and changing magnetic fileds (and seperated electric charges, of course) induce an electric field. What we need is a current. A current is an ALIGNED motion of charged particles (i.e. electrons) with respect to other (charged) particles (i.e. ions). If a plasma moves that way, you need magneto-hydro-dynamics to describe it properly.
But here is the point: Our gas cloud was at rest (we can assume that – just place yourself in the frame of rest of the gas cloud). Here comes the heating – the atomes get ionised and begin to move randomly due to the heat. If we have no “external” force to seperate the electrons and the ions from each other there will be no aligned motion and thus no current. What will happen is that the ions will capture another electron (-> recombination) and will emit light what we can detect. Then comes another photon and will re-ionise the atom which will recombinate again – and so on.
What we get here is a cloud of particles becoming ionised and neutralised again. There is a plasma, of course, but electric fields do not become larger than the Debye-length, so overall there is no current.
And why produced I this long text?
Well, finally: There is no need to describe the plasma with magneto-hydro-dynamics. Overall it will behave according to the laws of thermodynamics (like a GAS), just with a little quantummechanics (ionisation < -> recombination). And referring to point ONE, astronomers don’t see the point why they shouldn’t call a thing behaving like a gas just as a “gas”.
This is all about a “strange naming” by astronomers and a plasma behaving like a gas.
(Well, I think this is the story – quite long, sorry
)
August 29th, 2008 at 4:17 am
Sorry, I should have read it again… there are some mistakes with the english… “recombinate” means an ion capturing an electron… I’m sorry!
August 29th, 2008 at 6:32 am
Is Almach a true multiple star system with all 4 stars being gravitationally bound to each other?
How does the orbit look like? Is it weird? Or just 2 in the centre with 2 revolving around them?
Talking about multiple star system: What is a reasonable range for the angular diameters of the suns as viewed from a hypothetical planet within the habitable zone?
(That scene with two suns in StarWars freaks me out, for multiple suns not frying the planet surely must imply that one appears much smaller, right?)
Imagining that all four stars were still in their prime (i.e. not white dwarfs), then what would reasonable angular diameters be for a planet within the habitable zones of such as system?
August 29th, 2008 at 7:12 am
Well put, Doc! Now I understand the whole plasma/gas nomenclature war thingie!
If it looks like a duck and quacks like a duck, it’s called a duck, even if it’s really a plasma duck!
Rich
August 29th, 2008 at 7:13 am
[...] Green objects in space — Soylent Green is people! (Actually, some cool astronomy stuff for you hard sf types, or you “green sun” fantasy types.) [...]
August 29th, 2008 at 7:29 am
@Richard Drumm
If it’s an undead duck, would it be an ectoplasma duck?
August 29th, 2008 at 8:37 am
@ shane
What is Roger Federer (Swiss)if not European? ( He won five Wimbledon finals in a row) and Nadal (Spanish) won four French open finals in a row and then won Wimbledon this year! In fact in Europe we haven’t seen a Yank (Roddick)or an Aussie (Hewitt) win in quite a while
August 29th, 2008 at 10:28 am
Madge, the Swiss are non-ionized and are effectively neutral and therefore don’t count.
August 29th, 2008 at 10:42 am
So Roger Federer is only considered a European by astronomers? I’m so confused.
August 29th, 2008 at 11:02 am
Almach is multiple star system in Andromeda (though to the eye it looks like just one star), and its components do just this.
It took me a moment to realize you meant the constellation, not the galaxy. I was really impressed that we’re able to resolve multiple star systems a couple million light-years away.
August 29th, 2008 at 11:04 am
[...] Followup: Green objects in space | Bad Astronomy | Discover Magazine A while back, I wrote about why there are no green stars in the sky (you should read that post first; some of the concepts below are explained there). But that’s not to say there are no green objects in space. There are! (tags: wissenschaft weltraum space science weltall farben) No tag for this post. [...]
August 29th, 2008 at 11:12 am
Green stars do exist and are cataloged. Phil, I’ll bet you an ice cream Sundae on this.
[Note to any reader: please don't quote me just yet on this.]
For more on this topic, someone once wrote a great article in Astronomy magazine called “Alien Skies” that gave good evidence for green tendrils in space. That someone was….. ta dah! The Bad Astronomer.
August 29th, 2008 at 11:37 am
@ Nathan Myers:
First, it is seriously offensive to call science and scientists dishonest, when the whole process is set up to guarantee that it won’t happen much.
Second, as DrFlimmer so eloquently have described it, it is AFAIU a universal process that produces this; you don’t even have to resort to parsimony to explain why neutrality is the default expectation.
Besides, there is the observational evidence. If there were organizing currents I would expect it should show up as recognizable doppler shifting of the emissions. (Which, as we heard in the post, can be distinctive as regards spectra.) I assume that there is no evidence of that in these types of systems.
And perhaps a dash of classic EM? A plasma would have a sheath region at the boundary, which explains why electrons doesn’t leak away. (As a leak will set up a positive counter potential on the plasma.)
Btw, I believe you want to say your “recombinate” should technically be “recombine”, as in “the atom will recombine again”? And my spell checker insists that it is “ionization” in Phil Plait’s US english. [And for my part it is "Doppler shifting" after the scientist of course, but I think it is a capital bore to bear with english capitalization.
]
August 29th, 2008 at 11:44 am
@Richard Drumm:
You put it well yourself
Btw:
As you can guess… a “I” stands for a neutral atom, hydrogen can only be ionised once (so HII is a fully ionised hydrogen-gas/plasma), a fully ionised helium-gas/plasma is an “HeIII”-gas, and so on … got it? Good 
My explanation works exactly in so-called “HII-Regions” (H-two). (Check it out somewhere…)
And here we have the same “strang naming” again. Because the “II” stands for “once ionised” – it’s clear and obvious, right?
August 29th, 2008 at 11:46 am
PG, and others, it seems that the green imaging may be an accurate color depiction. Here is its spectrum…
http://oit.williams.edu/nebulae/spectra.cfm?source=NGC%206826
The two sharp spikes are green and red, and little else.
[Of course, the surface brightness might not be great enough to actually see the green color, regardless of telescope size, too. Then agian, perhaps it is bright enough.]
Pretty cool!
August 29th, 2008 at 11:47 am
Am I the only one thinking about Green Eggs and Ham right now?
August 29th, 2008 at 11:50 am
Phil:
Your explanation of the stars system Almach brought to mind an experience I used to have way back in the prehistoric days of the Apple IIc computers.
While working on all nighters getting seminar papers done and a thesis written, I would be staring at a green-on-black Apple II screen for hours. Every so often, I’d have to look up and the white walls of my office and the papers with my notes would almost glow an orangy-pink. The first few times, I blamed it on cheap caffein.
Later I realized it was some sort of color compensation. I understand that is why surgical scrubs were changed to from white to aqua green, because after staring at the red insides of patients, surgeons would find all the whiteness around them turning green and it was pretty dizzying to some.
August 29th, 2008 at 11:58 am
@ Torbjörn Larsson:
First of all: THANKS!
And the dash of EM…. well, you can do it if you like, but it is not necessary to take the “boundaries” into account in most cases. The most “interesting” things will happen in the whole cloud. And the clouds can be VERY big (few parsecs or even bigger!). So boundary-effects will be quite negligible.
This is another thing in astrophysics: Not only strange naming, but also what is considered negligible or what is a good “error” in your calculations. 20% error is quite good because you have no choice to remake your “experiment”. And due to the large scales of most astrophysical objects (like gasclouds, stars, galaxies or the universe itself) there is no need of regarding every “little boundary” all the time.
It also depends on what you are looking at. I.e.:
Space is a perfect vacuum, even near to earth. But if you study the behaviour of the atmosphere and the magnetic field you have to take the few particles (5 pccm) into account (compared with 10^23 pccm on the surface of the earth!!).
August 29th, 2008 at 1:32 pm
@[b/]Nathan Myers -
Actually, your son’s visual condition lays well inside the meaning of my post. And, a very good example, at that.
Is there anyway that modern medical technology has a way to correct your son’s vision?
August 29th, 2008 at 1:55 pm
MESSAGE FOR PHIL:
Sorry for yelling, and I apologize in advance for posting something irrelevant to the topic. I’m only posting here since I think Phil reads these posts. So… Phil, (or anyone in the know) where did the Ed Mitchell-UFO post go? You know, the one with the big Michael Horn debate. There were a few people (Todd, Greg in Austin, Celtic etc.) that spent a lot of time building a great case for critical thinking. Will comments continue to disappear in the future like that? I’m not overly worried about it since I only chimed in every now and then on that particular post, but I feel bad for the folks that typed pages and pages to prove their point, only to have them vanish. Michael Horn included. Or maybe the problem is with my browser… but I can’t find anything. And yes, I’ll feel like a toolbox for posting this if the problem is on my end. Thanks in advance. If you could, please post here rather than email me since I gave a fake email address. Damn spam… thanks.
August 29th, 2008 at 2:14 pm
@Harold
That Ed Mitchell/UFO thread with Mr. Horn doesn’t come up for me, either. I’ve been wondering what happened to it. The antivaxxer thread appears to have gone missing, too.
August 29th, 2008 at 2:28 pm
@ Todd
Glad to know it’s not only me having issues. I paged back to the original article thinking that maybe I had a bad link bookmarked, but the 1098 comments that are supposed to be with it are gone. It’s sad really, and I bet some people will now be hesitant to write lengthy and informative posts when there is a possibility of them disappearing at any given moment. 1098 comments disappearing = a lot of wasted time for a lot of folk. Such a disservice. Maybe Phil can smack an I.T. guy around at Discover and get it fixed.
August 29th, 2008 at 2:58 pm
@DrFlimmer:
Okay, I should have considered that electron leakage and concurrent small positive potential is a very, very, … , very minuscule part of the description of plasmas light years across. [I have grown up amongst mesoscale cold plasmas, in plasma processing systems.]
Um, now I see this picture of plasmas without sheaths, as in “bare”. Slightly pornographic IMO.
August 29th, 2008 at 3:10 pm
Well, don’t show those plasmas to your kids
Oh, and your apology is accepted
August 29th, 2008 at 3:47 pm
@Harold and Todd:
C’mon, dudes. Open your eyes. Those UFO posts didn’t disappear…they never existed! At least that’s what the Government wants you to believe. Trust me, this was predicted by Billy Meiers back in, oh, 1842. Sheesh.
August 29th, 2008 at 4:00 pm
@ kuhnigget
Sorry for leaving you out. You also invested a lot of time on that thread. Maybe it was all an illusion!!
August 29th, 2008 at 4:30 pm
Probably not an illusion, but given the nature of the “other side” of the argument, no doubt fairly pointless. I wonder what it’s like to debate with people who actually might be open to reasoned persuasion? Oh well, as Mr. Gumby would say, “My brain hurrrrrrts!”
That nebula sure is green, tho. (Topic lock engaged…)
August 29th, 2008 at 5:34 pm
@kuhnigget
No, the thread definitely existed, but I guess the aliens just abducted them. They’ll probably be back, but they’ll be all parsed in weird ways.
August 29th, 2008 at 5:39 pm
Speaking of which, the secret of the hot population of electrons in technically used cold plasmas may finally have been revealed.
Not surprisingly it is a sheath effect.
August 29th, 2008 at 5:44 pm
Come on, Dr. Phil!! Hook some brutha’s up. Oh, and nebula’s are sweet. Green too.
August 29th, 2008 at 5:46 pm
@ Todd
Haw haw! “Muh post done got analyzed!”
August 29th, 2008 at 5:47 pm
Todd W. eat me to it.
Alien abduction of thread…
August 29th, 2008 at 6:13 pm
@kuhnigget and Michael L
I just had a revelation… the aliens aren’t flying around, buzzing Phoenix, mutilating cows and abducting people off of lonely country roads; they’re in the servers at Discover!
August 29th, 2008 at 7:03 pm
@DrFlimmer: Your explanation is familiar. However, it amounts to what I said; i.e., if you assume at the outset that only thermal processes can possibly be occurring, your conclusion will be that only thermal processes are occurring. In the meantime, you should know that when you say “MHD”, you’re referring to a profoundly unphysical approximation whose only merit is that neatly avoids the details that make real plasma interesting. (A unit of MHD seems to be part of the standard astronomy curriculum, which may be worse than no exposure at all; ignorance is easier to fix than knowing what “ain’t so”.) If you call all plasma “hot gas”, and all charged-particle motion “rains” or “wind”, you program yourself not to perceive profoundly interesting phenomena happening right under your figurative nose. I expect it will be another two generations before astronomy students are allowed to mention them without being called nasty names by Phil and his brethren.
@Don: Actually that’s madge’s son. But it’s genetic; I presume there are damaged genes on the X chromosome. Maybe the corresponding proteins could be provided, but you’d need to get the right cells to take them up. Someday the requisite genes might be packaged in a virus coat that targets at the right cells, and arranged to be expressed in the right amounts and places, but it doesn’t seem easy.
August 29th, 2008 at 9:03 pm
One of the more famous aspects of these green planetary nebulae was the discovery of the green emission line at 500.7 and 495.9 nm by Huggins in 1864. These lines defied explanation for over fifty years, lending speculation they were due to a new element, which was named nebulium. In 1927, Ira Bowen proposed these lines were formed by otherwise ‘forbidden’ transitions between meta-stable atomic states of oxygen and nitrogen. In 1931, the transitions were demonstrated under laboratory conditions.
More about the history and similar connections in the paper linked on the website above “The Cosmos in Your Pocket: How Cosmological Science Became Earth Technology”.
August 29th, 2008 at 9:12 pm
No comment on Palin? Huh. There’s the whole ID angle, Phil.
August 29th, 2008 at 9:35 pm
@QD
Isn’t he at DragonCon? Give him time…
August 30th, 2008 at 12:11 am
Isn’t he at DragonCon?
Oh yeah. Der.
August 30th, 2008 at 3:02 am
Thankyou! Bad Astronomer Thanks!
I’ve been waiting for this post for ages – very glad to read it at last!
:-)
August 30th, 2008 at 3:17 am
Wrote the BA :
“The planet Uranus looks green too, but that’s because its upper atmosphere has lots of methane, which absorbs red light. Again, it’s not a star so it doesn’t count.”
But wait Ouranos (to use the proper Greek spelling of this Greek named celestial “wanderer”)*is* in fact listed as a star!
Really. I do believe Flamstead first originally included it on his charts as ‘34 Tauri’ – that was of course before Wilhelm Herschel detected “comet” Ouranos (or Georgium Siderus – “George’s Star” – as he wanted to call it in honour of King George III!) on the 13th March 1781 before it’s planetary nature was finally determined.
Much the same thing also happened with Neptune too …
Actually I think several astronomers mistook Ouranos for a star back before Herschel’s official discovery of that planet.
August 30th, 2008 at 3:28 am
Source for Ouranos’es 34 tauri – which happened in 1690 BTW. – &for thedtae of Ourmanos’es discovery is Isaac Asimov’s “Uranus : The Sideways Planet” , Collins – National Library of Australia, 1988.
On Beta Librae -Zubeneschmali one theory is that itscolouringresults foom the stars light actually being from a combined ‘blue dwarf & yellow giant seen at right angles’ producing its green~ness.
Source : ‘Astronomy Now’ magazine, August 1996 by Clemishaw.
What do you reckon BA anyone else? Plausible? Any further news / ideas?
August 30th, 2008 at 3:33 am
Typos &spacin’ — Arrghgh!! Wish Icould edit here .. Sigh
————-
On Beta Librae – Zubeneschmali – one theory is that its colouring results from the stars light actually being from a combined ‘blue dwarf & yellow giant seen at right angles’ producing its green~ness.
—-
Sorry, I sure wish there was a better way to make corrections here .. Hint, hint!
August 30th, 2008 at 5:35 am
Yet we hear that the thermodynamical behavior of nebulae is lacking “interesting” physics.
@ Nathan Myers:
Now you are misrepresenting the commenters as well. DrFlimmer covered the EM processes in his description.
But even if it were true, if the model predicts the data, and there isn’t a competing model, it is correct. You don’t need to assume all possible processes when explaining, say, why a dropped stone fall to the ground.
Duh! It predicts physical data, so it is physical.
Perhaps you mean to say that there are more realistic models, in the sense that they are more fundamental.
But surely that can’t be a beauty criteria when comparing similar models – we know that, say, GR is an effective as opposed to fundamental theory of gravitation, yet we don’t go around to call it “a profoundly unphysical approximation” that “avoids the details that makes real” gravitation “interesting” when we lack better models.
Btw, I would like to have a description of what you see as “the details that make real plasma interesting” and how it applies to observations of interstellar plasmas. Just to see if we can agree on the observed facts.
August 30th, 2008 at 6:02 am
@ Torbjörn Larsson, OM
We understand each other
I was about to say the same.
– the same as is with lightyears, they are both length-scales!). These are conditions an earth-bound plasma cannot achieve! So the conditions are different and there is no need to use every single piece there is about plasmas.
. But it works and describes the world as we see it. If we cannot hold to it anymore, we will look what the quadratic approximation will yield and so on.
One point I can add (maybe two) : The densities in a gas cloud in outer space are really low. In every earth-bound experiment they would be a “more than best” vacuum with about 10^6 particels pccm. And as I said these clouds are LARGE.. many parsecs across (and no, parsec is not a time-scale as Star Wars implicates
And there is the second point, allready mentioned by Torbjörn, but I want to emphasize it:
There is NO need to refer to the “deepest and most fundamental” theory available. We have GR but Newtonian Gravitation works VERY well for earth, so why not use it? It is easier to calculate it than GR, MUCH easier! (Ok, agreed. For GPS we actually need GR!) And so it works with everything else in physics.
Because this is what Physics is all about: The ability to reduce your problem as much as you can and to make it as easy as you can to calculate something. This is how physics differs from mathematics.
Physics is mostly a linear approximation – as long as it works. Mathematician will run out the door screaming seeing such crimes against mathematics
Oh… and one last thing:
Torbjörn: The link you postet leads to an article about physicists of the Ruhr-University in Bochum, Germany. Well, this is exactly “MY” university, where I am studying in the 3rd year
August 30th, 2008 at 6:37 pm
Why are plants green ?
According to Fred Hoyle, green plants on Earth originated from unicellular
photosynthetic organisms that came aboard comets.
These unicellular photosynthetic organisms were born in giant molecular clods where the
light from neighboring stars was reddened by the intervening dust.
They needed a green photosynthetic pigment – chlorophyll , to absorb the red light optimally .
Present day plants descended from these unicellular plants
that came from space.
Some plants developed photosynthetic pigments of other colors, but
chlorophyll had a head start.
August 31st, 2008 at 8:54 am
I’m just curious as to what effect a gas cloud like this would have on a spacecraft flying through it, if any? Would it be even noticeable?
August 31st, 2008 at 9:03 am
@ Michael L
Probably not! Those gas clouds are dense for space conditions, but a perfect vacuum for earth conditions. I guess a space craft would not notice it anyway.
On the other hand: If you have some high-energetic particles in that gas, they would be a threat for the spacecraft – same as solar flares.
But under “normal” conditions I think they are not very effective…. unless those clouds behave as in StarTrek, of course
August 31st, 2008 at 11:21 am
Michael L:
August 31st, 2008 at 11:41 am
Damn it! I tried to submit an answer to Michael L’s question without a direct URL link to source, but it STILL got held up for moderation!
So, I’m submitting my answer again without the bloody URL!
Michael L:
According to NASA, the International Space Station (ISS) orbits at nearly the same height as aurora borealis/australis, sometimes passing over them, and sometimes right through them. However, the auroral electron and proton streams pose no direct danger to the ISS.
August 31st, 2008 at 12:24 pm
For some reason the “blockquote” HTML didn’t work properly in my previous comment (”awaiting moderation” at the time of writing this) before last. I wish the web-master of this site would provide commenters with the falcility the edit/delete one’s comment, as is available on RichardDawkins.net.
August 31st, 2008 at 12:34 pm
ERRATUM: For some reason the “blockquote” HTML didn’t work properly in my previous comment (”awaiting moderation” at the time of writing this) before last. I wish that the web-master of this site would provide commenters with the falcility to edit/delete one’s comment, as is available on RichardDawkins.net.
See. This is what I mean!
August 31st, 2008 at 2:04 pm
Thanks Guys! That answers my question.
August 31st, 2008 at 4:35 pm
You’re welcome, Michael L!
P.S. Furthermore, before somebody points it out to me, I should have written facility, not “falcility”! Bloody typos!
August 31st, 2008 at 10:22 pm
As noted along with Almach are a few other multiple green stars where at least one component appears emerald. The companions to Antares – Antares B which is a type B “blue dwarf” star – and also Rasalgethi B (Alpha Herculis B) again the dimmer B type companion to a red supergiant – both appear green or green-ish to at least some observers.
Zubeneschmali (Beta Librae) is also a type B star, B8 to be precise, which is exactly the same spectral class as Rigel which appears quite bluish although Zubeneschmali is a core hydrogen burning or main sequence (luminosity class V) dwarf unlike Rigel which is instead a core helium fusing bright supergiant (luminosity class Ia) star. Another example of a brightish B8 V star – also a single blue dwarf is Sirrah or Alpheratz (Alpha Andromedae) which again appears bluish white and NOT verdant environmental in hue. Rigel’s companions – that star is actually at least a triple star system of the main supergiant (Rigel A) and two dwarfs (Rigel B & C) both B9 V stars – both usually described as blue or white.
For me personally, Zubeneschmali does sometimes appear green although at other times appearing white – not sure whether imagination and or atmospheric affects are in play here too!
Incidentally, located about 2 degrees from Zubeneschmali is Gliese 581 (aka Gl 581 or GJ 581) that nearby red dwarf star with the much hyped “earth-like” exoplanet (although its more likely to be a supersized Venus than anything “Earthlike”; probably more a Venus-crossed-with-Neptune in fact.) This is very close in the sky to Zubeneschmali but despite its nearness to us, Gliese 581 shines at only magnitude 10.6 in our skies, far dimmer than the faintest objects (mag. 6) visible to the unassisted eye. Gliese 581’s three exoplanets are, of course, well & truly undetectable without specialised equipment but just knowing they’re there is pretty neat!
NB. Source for Gl 581’s position : “Spying stars with Extrasolar planets” Page XIII in “Sky Guide 2008” lift-out supplement with ‘Astronomy’ magazine.
As well as the Greenness factor and the nearby Gliese 581 planetary system, Beta Librae – Zubeneschmale as its also sometimes spelt (the name means “northern claw’, a reference to the nearby constellation of Scorpius to which all the stars in Libra once belonged.) – has one further distinction :
It is one of the few stars thought to have changed brightness over historical times. Zubeneschmali was once described as being as bright as Antares – as I’ve noted also in that first “no green stars?” thread. Whether or not that has anything to do with its famed emerald glow is another question … Could it have? Anyone?
One thought may be that a massive Coronal Mass Ejection from Beta Librae perhaps left a surrounding cloud of gas scattering & dimming its light to make it seem green? What do folks reckon?
Finally, its also worth noting (again, again) that our own Sun does sometimes appear green – albeit just for a fraction of a second or so during the Green flash!
August 31st, 2008 at 10:33 pm
IVAN3MAN said on August 31st, 2008 at 12:34 pm :
“ERRATUM: For some reason the “blockquote” HTML didn’t work properly in my previous comment (”awaiting moderation” at the time of writing this) before last. I wish that the web-master of this site would provide commenters with the falcility to edit/delete one’s comment, as is available on RichardDawkins.net.”
Hear! Hear!
I couldn’t agree more – in fact I’ve (StevoR too) been calling for this for ages!
Please, please, please Oh great & powerful; Dr Phil Plait you BAd Astronomer you, please for pity’s sake, for heavens sake, for all our sakes :
LET US EDIT HERE!
Sheeesh, I know I go on about this but really .. it is just so #@!#@!!#!@%&^*^$# frustrating…
…. Yeeeeaaaaarrrrrggggghjhjhjjjj!!!
September 1st, 2008 at 12:24 am
D’oh!
The link to Kaler’s ‘Zubeneschmali site is the same one listed by the BA already under the first word of this :
“Zubeneschamali is the second brightest star in the constellation of Libra. It’s somewhat hotter than the Sun, and some people claim it looks green to them, while other say it looks white.”
I should have checked the link at the top of this article *before* I made my last post – which btw. hasn’t yet come through here – although it has according to the “duplicate comments” filter (because I tried to post it again thinking it hadn’t worked ..) Ah, the frustrations of this blog comments thingummy – not meaning to seem ungrateful because I love this blog & forum thingy!
But ..well.. there are some things that could be done better here too!
Out of sheer morbid curiousity, why is it posts here sometimes appear the “awaiting moderation” disclaiming message & other times just don’t show up at all – at least for a while?
Please, could we get some consistency on this? (Personally, I’d prefer the ‘awaiting mod’ message – so we know where we stand & can see that what we’ve posted has come through.)
A better, quicker way of indexing old items / posts here would be nice too as would a html capabilities list – or better yet having the italics, bold etc .. icon buttons a la normal computer typing without needing the > < whatever brackets - &needless tosay lamost - if only we could edit or at least preview our posts.
Oh & getting the old site back would be betetr too or atvery least telling the "Discover" mob to provide us with some left hand margin not allsquashed itno the side format would be nice as well!
Not meaning tocomplain but just giving some hopefully constructive criticism for the Bad Astronomer & others to consider. Either way, many thanks for an eccellent blog anyway.
PS. 1 more thought for the Bad Astronomer any chance some of the best posts here could be compiled into a non-fiction book in themselves?
I’d rather the printed form & a good book than feel stuck to an annoying, slow to load, frustrating, unreliable, @!@#!@!!#@!% computer anyday!
September 1st, 2008 at 12:59 am
… Of course the book (I’d suggest ‘Best of the Bad Astronomy blog’?) wouldn’t stay as up to date like the blog does but then the posts that survive the test of time & are particularly informative & interesting would remain and people would be able to easily find, catch up on & stumble across ones they might have missed!
Book form does have its advantages too – you could, for example compare all the “best photos of year X” columns easily & see how some stories have evolved over time and much more. Plus they’re easier & more fun to read on the train, in bed, etc ..
So for what little its worth, here’s ten or so superb articles which Dr Phil Plait has written & posed here which I’d suggest deserve proper publishing and including in this hypothetical book for example :
1) The Best photos of 2007- 20006 -2005 etc ..
2) The Puzzling planetary (SuWt2) thread – “One ring to fool them all”
3) “The Red Dwarf that Roared” thread (EV Lacertae’s huge flare)
4) This & the previous “No Green Stars?” threads.
)
(Which btw. I consider two of your best ever, BA!
5) The Gliese 581 “earthlike” exoplanet thread
6) The “Welcome our Tiny Family” “thread (The borderline star or brown dwarf with low mass planet -MOA-2007-BLG-192Lb) & some of the other threads on exoplanets such as mapping one of the Hot Jupiters, etc ..
7) Some of the pareoilda threads eg. the face in the A-bomb, in the wood, “angel” at the fair ground etc ..
9) Some of the Pluto / Planetary Definition threads & also the KBO /TNO discoveries like Eris – which I’d call the tenth planet as Pluto is the 9th planet* & Sedna (BTW. Did you post on Sedna, BA?)
10) Your Galapagaos trip diary & also some of your movie reviews & Dr Who /Trek /SF TV series comments.
Of course, there’s also far more you could include – enough for quite a few “Best of the Bad Astronomy blog” books in fact. So we could have Book I, Book II, Book III, etc ..!
Please I really reckon this is worth considering & would help you reach a wider audience as well as just on-line folks.
* Yes, I know there’s also planet Ceres to include which I’d call the 4 & a halfth planet – just like Isaac Asimov did! Planets : the more the merrier!
________________________
“… he had left out a planet. It was not his fault; everyone leaves it out. I leave it out myself when I list the nine planets, because it is the four-and-a-halfth planet. I’m referring to Ceres; a small but respectable world that doesn’t deserve the neglect it receives.”
(Nor might I add does Pluto – Ed!)
Source : Page 63, chapter 5 “The World Ceres” in ‘The Tragedy of the Moon’ by Isaac Asimov, Mercury Press, 1973.
_______________________________________________________________________
Hmm .. Now back to the topic & sorry for going a bit off topic there folks .. Hope y’all don’t mind too much & hope you like my suggestion.
September 1st, 2008 at 1:23 am
DrFlimmer: I wonder where you would find a perfectly uniform non-ionized gas cloud to heat up radiatively into a purely-thermal neutral plasma cloud. In every cosmological model I know of, ionized is the starting state of every scrap of (hadronic) matter in the universe. Uniform and history-free is hard to come by. A non-uniform plasma cloud (i.e., any real cloud, anywhere) is necessarily laced through with sheaths, as broken up into cells as a slime-mold. No, you don’t get to neglect sheaths.
About MHD: a model that is incompatible with Birkeland currents can hardly be called first-order; it’s more akin to Aristotelian gravity than Newtonian. We don’t “lack better models” than MHD; we have PFD, in which empty space is not infinitely conductive. It’s perhaps unfortunate that it’s “fiendishly difficult”, but surely that’s the astronomers’ problem, not the plasma’s.
September 1st, 2008 at 2:41 am
Yes, of course “plasma” is the starting state of the cosmos. Just think about the tremendous temperature. But roughly 300.000 years after the Big Bang the temperature was too low to be able to ionise anymore. So the protons and electrons recombined to neutral atoms which then just “sat” there and waiting for dark matter to attract them (if I may say so
). So there are our neutral atoms.
Later came the age of “reionisation” which, of course, didn’t reionised ALL atoms. It was the age of the first stars to come up.
Well. I know that the intergallactic medium is mostly hot gas (plasma). I must say I don’t really know where it gets its energy from – maybe “galactic” friction (tidal forces, etc).
What I was refering to with my description above where HII-regions, regions of star formation. O and B stars are so big that they have a short and very violent life. Theire surface temperature is quite high. In fact it is high enough to ionise the surrounding hydrogen (the photon energy is mostly higher than 13,6eV). But Hydrogen is optically thick to UV-light. So all the emitted light of the star will be captured. Assuming a uniform distribution of the hydrogen around the star the ionised region is well defined by the “Strömgren-sphere” which gives a hint about the size of the ionised region (the HII-region).
We are able to detect the HII-region because of the recombination which will happen like a cascade of the electron down to the ground state in the hydrogen atom. The likeliest transition will be from state 3 to state 2 (in the optical spectrum!) which is the H-alpha-line at roughly 650nm.
So this is the model. Of course it won’t be that easy out there. You have to take into account that the distribution is not unifiorm, angular momentum must be considered. But most of the story is in the described model above.
And again: Those gas/plasma clouds are extreamly big!! Sheaths are indeed quite negligible (if you just stick to the center, for example).
And once more: It is neither always necessary nor is it useful to refer to the “best” model you have if you are able to explain what you see with an “easier” one. If you come to a point where your easy model cannot go further – ok, stick to the “better” one.
I must also confess that I never heard of PFD (also a short check via wikipedia and google didn’t help). Would you tell me what it is, please?
September 1st, 2008 at 9:10 am
Herr doktor flimmer:
There’s a good reference forum on plasma cosmology on the JREF site. search for “plasma cosmology” and you’ll find it.
Unfortunately, while there may be something to parts of it, a lot of the theorizing seems (to me, admittedly no expert) to be a mix of science and rather a wee bit of woo-woo.
I’m sure Mr. Myers would disagree. No dis intended, Nathan. Peace on ya.
September 1st, 2008 at 9:11 am
damn. lots of italics.
September 1st, 2008 at 9:11 am
double damn!
September 1st, 2008 at 9:12 am
well shucks! now I’ve done and italicized the whole bloody thread! dunno how to stop it, folks.
September 1st, 2008 at 9:46 am
Aha… it happens.
September 1st, 2008 at 9:51 am
Charged characters all lined up in one direction… we’ve been plasma-ed…
September 1st, 2008 at 1:22 pm
@ kuhnigget
DrFlimmer will do
Well, I read through a thread about “plasma cosmology” at JREF for over 2 hours now. Quite interesting (not the idea itself but the discussion
). Assuming that earth-bound physics aply everywhere unless it is gravity – well, that is… (I don’t know a word), weird.
.
I guess I have an idea what this stuff is about, thank you for that! I haven’t heard of that stuff until now, and cosmology is a thing I am very interested in… PC hasn’t found the way to Germany yet, or I am visiting the wrong sites
September 1st, 2008 at 2:46 pm
kuhnugget: I’m no fan of “woo-woo” either. Unfortunately dark matter and dark energy are the father and mother of all woo-woos.
DrFlimmer: PFD = plasma fluid dynamics. I wouldn’t know where to find a uniform or symmetric distribution anywhere in this universe. (Remember when a supernova was supposed to be spherically symmetric? Quaint, no?) . It doesn’t matter how big the cloud is, or what’s at the “center”. The action is at the cell boundaries.
It’s easy, if it’s what you prefer, to ignore effects; just ignore effects. It’s extremely popular, nobody will criticize you. But it’s not science.
It amuses me to contemplate stars heating the ISM gravitationally. You are aware, are you not, that it’s a conductive medium moving in the galactic magnetic field? Can you suggest how you would prevent current flow?
September 1st, 2008 at 4:00 pm
@ DrFlimmer:
Sound like a good one, eh?
September 1st, 2008 at 4:32 pm
@ Mike:
According to Fred Hoyle abiogenesis consists of complex cells assembling de novo. (The junk yard argument.) He was an astronomer, not a biologist.
The first photosynthesizing organisms on earth neither produced oxygen (so didn’t need modern chlorophyll systems) nor were their simpler photo active compounds green. Here is a modern astrobiology primer on the different pigment systems we are likely to observe by future studies of other biospheres reflected light:
So plants are green on Earth surface because they absorb such photon energies with slightly less efficiency. Meanwhile they have other colors elsewhere:
We understand that green plants are adapted to the modern atmosphere:
Finally, as in contrast to Hoyle, we know how photosynthesis evolved on Earth:
Dust would tend to produce some thermal photons, but it is still a huge difference between cold molecular clouds ~ 10 K to habitable atmospheres ~ 300 K. Famously bacteriochlorophylls are purple, not green, red, yellow or brown.
September 1st, 2008 at 5:01 pm
@ Nathan Myers:
Of course not, they are the largest parts of standard cosmology, and have both been observed to high significance during the last year or so. (Bullet et cetera clusters for dark matter, the Integrated Sachs-Wolfe effect for dark energy.)
None of which applies to the “electric universe” pathetic pseudoscience.
AFAIU DrFlimmer there aren’t any cell boundaries, as electrons will have to leak over the large distances involved to set up potentials. And I bet there aren’t any observational evidence of charged “cells”; I have asked for some time now.
Absence of larger scale charge separation would do it, wouldn’t it? You would need local active mechanisms akin to cold plasma electrodes to drive a local current through, I think. That is btw how I understand currents gets going in our planets flux tubes, like the one connecting to Io.
Btw, those galactic magnetic fields were generated by rotational acceleration caused by gravitation, weren’t they? So how do you think they would overcome their generating gravity on larger scale, or on smaller scales as they were weak?
September 1st, 2008 at 10:39 pm
@[b]Nathan Myers[/b]
“@Don: Actually that’s madge’s son. But it’s genetic; I presume there are damaged genes on the X chromosome. Maybe the corresponding proteins could be provided, but you’d need to get the right cells to take them up. Someday the requisite genes might be packaged in a virus coat that targets at the right cells, and arranged to be expressed in the right amounts and places, but it doesn’t seem easy.”
Thanks for correcting to [b]Madge’s[/b] son. Sincere apology.
Umm, would genetic manipulation actually rectify the condition at the time of manipulation? Is there any surgical, medicational or other new techniques, other than genetic manipulation, which might remedy his conditon?
Hope you Labor Day Holiday enjoyed by you, your families, and friends.
September 2nd, 2008 at 1:04 am
@Torbjörn: If you were cared about the subject, you would know the papers well. If you were actually interested, you would already have located and read some. As it is you have revealed your intentions. If this were a scientific forum, citing papers would be both appropriate and obligatory, but it is just a fluffy telescope-pictures blog run by a former (or might-have-been?) scientist turned impresario. Do you really believe that galactic magnetic fields are generated just by “rotational acceleration caused by gravitation”?
@DrFlimmer: I wish to be clear: You can explain any observation with arbitrarily weak models if you are allowed to be selective enough about which observations you choose to explain, and to rely on enough arbitrary assumptions that you know no one in your community will question. That’s where astronomy stands, at present; the makings of a science are there, but squandered. The pictures are great, enough so that astronomy’s budgets are in no danger, but of course the pictures are ultimately the products of engineering, not science.
@Don: I have never heard of any sort of intervention that can help color blindness. Anyway it’s far from a debilitating condition, except in a very few fields. It really is rude, though, to produce graphics in which key indicators differ only by red vs. green.
September 2nd, 2008 at 2:59 am
As I just found out the debate even goes on in the other post about the “massive monsters”.
And right there I postet something where I tried to explain the existence of the very WEAK galactic magnetic field. I said this:
“In galaxies we have neutral, cold gas and a small amount of ionised gas (plasma). The collision between the free electrons and the neutral atoms is much more efficient than the collisions between the protrons and the neutral atoms. So we yield a charge separation. Due to the rotation of the galaxies the current is aligned which is important. So we have a current and we get magnetic fields which are very weak – as we observe in galaxies. It’s almost like a dynamo. (I don’t know if this is correct, but it should be close to it
).”
Yes we have some currents in the galaxy, but they are well explained by the rotation of the galaxy wich IS a gravitational effect. There is no other way of producing these currents. Because you would need a potential-difference or a gradient in the plasma which would cancel out itself over time, I would guess.
One other thing that comes to my mind is conservation of charge. If we assume (and I guess we can do it – since we observe it on earth…) that there were made equal amounts of positive and negative charge in the “creation” of the universe (maybe a BigBang….. – even a plasma universe should have been created eventually) then there is no reason for a current being the first thing “in the world” – because I don’t see a reason for a charge seperation or a gradient. So there were no currents and no magnetic fields. How did they just “popped” up?
Oh, and btw: The heating of the ISM is quite simple and has nothing to do with gravitation. It’s the “hot gas” streaming away from the stars (->solar wind) heating it up. I was wondering about the IGM. But I think gravitation CAN heat up a gas cloud. Turbulence is motion, and motion is heat. So gravitational encounters may produce enough turbulence to heat the thing up – but as I said, I am not sure about this.
@Torbjörn
. Of course, german elite-universities have nothing to with Harvard or that sort – they are just getting a little bit more money for the research. The “Ruhr-Uni” is quite ok, but the standing is not excellent, but it could be worse 
I’m happy here. And as we see: Our physicists aren’t so bad at all 
Well, the “Ruhr-Uni” was very close to become a german “elite-university” but we failed
September 2nd, 2008 at 4:25 am
@Nathan Myers
Ah…is that why it was so hard to even get an encyclopedia citation from you in the “Massive Monster” thread? Because this is “just a fluffy telescope-pictures blog”? Oh, and a citation which you didn’t even read thoroughly?
Please don’t call others out for not providing scientific citations if you, yourself, are not willing to provide the same.
September 2nd, 2008 at 8:27 am
(Hanging his head in shame for forcing these damn italics on everyone.)
Moderators? It’s me! My fault! Can’t you fix it?
September 2nd, 2008 at 9:16 am
@kuhnigget
I can’t remember. Was it you who did it last time, too?
September 2nd, 2008 at 10:11 am
If he was then he IS the master of the italics
The sad news is that even the master doesn’t know how to remove his creation (maybe that was god’s fault 
)
September 2nd, 2008 at 10:37 am
@DrFlimmer
Getting rid of the italics would be easy. Just flood the world (server room), then there would be a shower of bright blue sparks as a sign that the server room would never be destroyed by flood again.
September 2nd, 2008 at 8:30 pm
September 3rd, 2008 at 4:16 am
@Todd W.: I didn’t criticize anybody for not providing citations. I criticized dishonesty, and namecalling, and hypocritical hyping of woo-woo, and credulous acceptance of predecessors’ idle speculations, but I didn’t demand any citations.
September 3rd, 2008 at 4:39 am
@Todd W.: Oh, and it was hard to get me to provide a link to an encyclopedia article because it’s a waste of time to demand or to provide a link to an encyclopedia article. The encyclopedia is right there, just look at it.
@DrFlimmer: I don’t pretend to know where current might come from. When you find evidence of current (e.g. a magnetic field), you know it’s there, and then you may seek to discover its origins. Theories are useful, but they come last.
September 3rd, 2008 at 5:12 am
@Nathan Myers
The implication in your post was that Torbjörn should back up his arguments with citations, that if his argument had any validity, he should provide some. To make such statements when you do not adhere to the same standard smacks of the very hypocrisy you criticize.
Hmm. I actually don’t recall demanding a link to an encyclopedia article. I was asking for links to scientific articles. I asked Phil to provide the same. After repeated back-and-forths over the subject, you finally provided a link, but even then that link was to an encyclopedia article, not a published scientific paper, and by your own admission you hadn’t even read the article.
The ultimate result, rightly or wrongly, is that you appear to have a weak case. You make statements condemning the larger scientific community that is interested in the topic (astronomers) without providing anything to back up your arguments. When pressed for links, you have hemmed and hawed and have yet to produce anything solid. As I already have, I will admit again that I am not versed in this area, but your arguments sound very, very similar in style to those used by other fringe groups (Creationists, anti-vaxxers, etc.). To whit, “the ‘experts’ are wrong, I’m right, no question about it at all.”
The arguments on the other side, by contrast, have tended not to say that you are completely wrong, but that there are other explanations that work to describe the phenomena. Yes, some of the plasma theories apply, but not completely necessary to describe the situation. It strikes me as a much more compromising position open to change as new data emerges.
September 3rd, 2008 at 1:45 pm
@Todd W: I explained quite a few times that, and why, asking for scientific articles about mundane facts is futile. Ask, instead, why Phil does his best to obscure those facts in his reporting, and to avoid applying them, and chooses instead name-calling and outright dishonesty (”anti-science”) when attention is called to them. Even if you are not equipped to evaluate the substance of a disagreement, you should recognize those as attempts to distract you, indicating a weak position.
Astronomy is only one branch of science, and has mores very different from most others. They seem to have taken to heart that none of their results actually matter, in any mundane sense, so long as they can provide pretty pictures and talk knowingly about them. As a result, they have become very cavalier about their foundational assumptions, and openly hostile to outsiders who call them into question.
The history of science is littered with the remains of insular communities. Behavioral and Freudian psychologists wasted the lives of whole generations of psychology students, and squandered the fees of generations of desperate patients. Thousands of paralysis victims died of old age and bedsores waiting for neuroscientists to reconsider the doctrine that nerves cannot regenerate. In this case, all that’s wasted are the careers of astronomy students, but that seems bad enough.
September 3rd, 2008 at 7:10 pm
@Nathan Myers
Given the nature of the debate just on here, it does not strike me as being a cut-and-dried issue as, say, the fact that I cannot walk through a solid wall. Walking through walls is something that I can test for myself. The nature of plasma in space is not. However, I can read what others have observed and do my utmost to gauge the validity of their research. If I don’t have some direct sources to reference on this, then all I, or anyone else reading these threads, can do is to weigh the opinions of the various posters.
Now, I have some basis for gauging the experience of at least one of these posters. Dr. Plait has mentioned in various places on this blog regarding what is studies and work has been. On the other hand, I know nothing about what your studies have been on this subject. Both of you sound knowledgeable about it, but I’m not just going to take your, or Dr. Plait’s, word.
So, again, given my position, as well as that of other readers, it is entirely reasonable to request links to articles that support the arguments. You say that it is a “mundane fact”, yet you have done nothing to bolster that contention. How many average people would consider it common or ordinary? The lazy or apathetic would just accept whichever argument sounds most coherent. The more curious would ask to see the evidence, even if the presenter says that it is ridiculous to ask for evidence for something so plain and obvious.
Since Dr. Plait made an initial claim and you made an opposing claim, I targeted both of you to provide links to support your respective claims. But, I will open it up and ask anyone arguing against you to also provide links to scientific articles that support their arguments.
September 3rd, 2008 at 7:11 pm
Just out of curiosity, Nathan, what is your science background? Since we know something about Dr. Plait’s it’s only fair that we know a bit about yours.
September 3rd, 2008 at 9:39 pm
I studied engineering.
There are no disputed claims here. I pointed out that it’s all plasma. Everybody else has agreed it’s all plasma. Phil insists on calling it “gas”, instead. The issue is, why insist on calling it gas when it’s not? DrFlimmer says that’s just how astronomers are, they like to call things what they’re not (e.g. calling oxygen “metal”). That’s fine within their little clubhouse — they can all wear funny hats, too, if they like — but this is a public forum, and when you say “gas”, people reasonably think you mean “gas”.
Still, it might be OK if Phil admitted that saying “gas” when he meant “plasma” was just a personal foible. Everybody has them (e.g. I like archaic ligatures). Instead, he attacked me and called me nasty names, and then, amazingly, insisted against all sense and reference books, more than once, that plasma really is just gas. Now, I’m an adult and can take being called names, but it makes me wonder what the name-caller and deliberate misleader is up to. Why does he insist on his misnomer, to the point of rhetorical violence? We can guess, but wouldn’t it be better if he revealed it himself?
September 3rd, 2008 at 9:49 pm
@Nathan Myers
Thanks for the education info.
One of the items that was in dispute in the “Massive” thread was dark matter and whether or not it exists. Phil has stated in various posts that dark matter is a current, likely explanation for the “missing mass” of the universe. You posted that dark matter does not exist and that the “missing mass” can be explained by plasma (IIRC). So, that is the topic I am referring to regarding disputed ideas.
Also, regarding the behavior of plasma in space (as opposed to in the lab or even in Earth’s atmosphere), that does seem to be an issue of disagreement in the threads.
Links to articles on those topics would be welcome.
September 3rd, 2008 at 9:55 pm
Actually I did not say it was Plasma but just insult me again that seems to be your version of proof.
September 3rd, 2008 at 10:57 pm
Nathan Myers:
If you don’t like Dr. Phil Plait’s apples, why the bloody hell are you persistently shaking his tree?!
September 3rd, 2008 at 11:12 pm
@Todd W.: Actually, I didn’t say dark matter doesn’t exist, or that “the missing mass” can be explained by plasma. I said the whole topic was speculation. Dark matter is about as interesting as epicycles or the Id; i.e. it’s not an observation, it doesn’t arise out of observations, it’s just an artifact of a failed theory. It hardly seems worth mentioning at all.
@Davidlpf: No, you just lied, trying to tar me as an antivaxxer. Dishonest name-calling, on cue. (How are those calculations coming along? Oh, gave up? Never started?) Quick, fetch the stick!
September 3rd, 2008 at 11:18 pm
@Todd W: … except as an example of that failure.
@MERDE!: If you don’t know, you might as well let Phil answer himself.
September 4th, 2008 at 5:05 am
@Nathan Myers
“i.e. it’s not an observation, it doesn’t arise out of observations, it’s just an artifact of a failed theory”
Sounds like you’re saying that dark matter doesn’t exist. Please provide some studies that show that dark matter i just an artifact of a failed theory, or that point up the flaws in the hypothesis of dark matter.
September 4th, 2008 at 5:58 am
NB.
Attempting italics fix with greater than sign / backslash ‘i’ lesser than sign ##@!!#@$@ htm,l code thiummy for gettingiotalics /bold /etc .. here ..
Will it work … Maybe not? Hopefully so?
September 4th, 2008 at 6:03 am
No. Durnit.
BA There are some annoying bugs on this & no editing capability!
Love your blog but please, please, please can we fix these infuriating gremlins? (Or better go back to the old blog host /server / whatchyamacallit & just improve that? This ‘Discover’ one ain’t the best & ain’t really growing on me either – they need to fix it up too. Eg. some left margin at least for starters please!)
September 4th, 2008 at 6:17 am
Oh well what I came here to post – again since it didn’t work first time was this :
Stellar expert James B. Kaler’s superluminously brilliant website (the source of the Zubeneschmali link quoted by the BA at the top here.) notes that one of the stars comprising Almach (Gamma –2 Andromedae) is also a green-ish (but via contrast?) star of type B8 :
“The orbit gives a combined mass for the three stars of 8.7 times that of the Sun which is consistent with advanced B8 and A0 dwarfs joined with a lower mass class A7 (or so) dwarf star about which nothing is known.”
So Almach or at least one of its components joins Zubenelgenubi in the B8 type “green” stars. Thus we have :
Zubenelgneubi – main genuinely green star candidate – B8 type hydrogen fusing dwarf.
Almach component star – also type B8 main-sequence (H -fusing) dwarf thatappears gren or green~ish but in a multiple star system & poss. contrast FXT with orange giant.
Antares B – also a green or green~ish B class dwarf (B8?) but in multiple & poss. contrast FXT with red supergiant.
Rasalgethi B – also a B class dwarf (B8?) but in multiple & poss. contrast FXT with red supergiant.
So could there be something to this B type green or green~ish stars thing and could the greenness of the Antares and Rasalgethi companions be at least partly intrinsic as well as contrast?
Although then again we have also got other B8 type stars that are NOT green notably Sirrah a.k.a. Apheratz (Alpha Andromedae) and Rigel A (B8 and blue) plus Rigel’s B & C two B9 & blue dwarfs. (Albeit though those dwarfs are, I think, spectroscopic not visual binary orbiting the main supergiant.)
Hmmm … Co-incidence or do some B type stars esp. B8 V really appear green? If so why only some & not others?
Suggestions or thoughts anyone?
(Link with Almach via Kaler’s site to be attempted to post here again next ..)
September 4th, 2008 at 6:29 am
No. Won’t post the link. Yikes, this is a pain!
Incidentally, I imagine somebody smarter or at least better intertoob-webbing skills than me (& the latter at least is well almost everyone else here I’d guess) has already tried the closed brackets html code technique & smarter things already. Can’t the moderators or ‘Discover’ people or anyone fix it though? Seems not so far ..
Try :
http: “double backslash” www “dot” astro “dot” uiuc “dot” edu “backslash”
~ kaler “backslash” sow “backslash” almach “dot” html.
$#@!!@@ computers!
September 4th, 2008 at 6:35 am
@StevoR
You can also put the website in the “Website” box when you post, then just tell people to click on your name. It’s another way to get around the auto-moderation filter for hyperlinks.
September 4th, 2008 at 7:21 am
Of course, there’s always the issue of what’s ‘blue’ to some folks could also be seen as ‘green’ by others!
Turquoise anyone?
(Eg. the colour of the old ‘Lleyton House March team (notable drivers – Ivan Capelli & Maurico Gugelmin) back in late 1980’s – early 90’s F1 racing to use an, admittedly obscure, example that sticks in my mind.)
Mach drivers 1988 Capelli & Gugelmin
September 4th, 2008 at 8:29 am
StevoR:
Check this out: Color Optical Illusions
September 4th, 2008 at 8:55 am
March (aka Leyton House) F1 team drivers 1987 – 1992
1987 Ivan Capelli
1988 Ivan Capelli & Mauricio Gugelmin
1989 Ivan Capelli & Mauricio Gugelmin
1990 Ivan Capelli & Mauricio Gugelmin
1991 Ivan Capelli, Mauricio Gugelmin & Karl Wendlinger
1992 Karl Wendlinger, Jean-Paul Belmondo, Jan Lammers & Emanuele Naspetti
Throughout this time their cars were painted in an aquamarine / turquoise colour intermediate between green & blue.
Hope this helps folks track down some image so y’all can see what I mean!;-)
September 4th, 2008 at 8:58 am
Oh & if its any help for the Americans here, Mauricio Gugelmin went into indycars for acoupleof seasons and I’m pretty sure won atleast one race there after the end of his F1 career.
September 4th, 2008 at 9:08 am
Todd W. said on Sept 4th, 2008 at 6:35 am :
“@StevoR – You can also put the website in the “Website” box when you post, then just tell people to click on your name. It’s another way to get around the auto-moderation filter for hyperlinks.”
Thanks! I’ll try that! In fact see above!
(The Almach link via Kaler’s stars site should now be there!)
Cheers!
Hmm.. folks go also find Kaler’s stars site and form viewing that his Alkmach (Gamma Andromedae) page via the link to Zubeneschamali (hypertext ain’t it?) at the top of this item. But of course, now they don’t need to. I hope!
September 4th, 2008 at 9:14 am
YES! Click on my name & you’ll end up at Almach! (A trip of about 355 light years!)
Neat trick, THX again Todd W.
Now all we need to do is figure out how to fix the italics here .. & then how to edit posts ..
September 4th, 2008 at 9:28 am
@StevoR
Not my trick. Picked it up in another thread (I think the Ed Mitchell one with all the Michael Horn posts).
September 4th, 2008 at 9:55 am
Okay – now clickon my name for alink to the Wikipedia Leyton House F1 team page which has an image of thecar and its colourscheme -aquamarine /turquoise , green /blue also y’see what Imean!
Other Wiki links incl. photos of the turquoise March F1 cars include pages for Ivan Capelli (who raced for Ferrari for one season – 92 as well!)
& For Mauricio Gugelmin (who won one Indycar race – in Vancouver 97.)
Designer Adrian Newey (who worked for much better teams later ..)
& for the original March team which was in F1 intermittantly for quite a while …
But this is getting wa-aay off topic again. (Not that I’m the only one guilty of that on this thread!)
My main point just about the colour of the car – is it blue or green or something you could describe as either?
So with the car, with the star?
September 4th, 2008 at 11:42 am
@StevoR
Blue car with a green nose.
September 4th, 2008 at 1:51 pm
@Todd W: Can you tell the difference between the statements “It doesn’t exist” and “I know of no reason to think it exists”? What sort of documentary evidence would you propose might be needed to support the latter, in general? I have already said that I don’t consider it interesting to talk about, except as an example, so I don’t propose to talk about it further. If you’re very interested in it, ask somebody else.
September 4th, 2008 at 2:26 pm
@Nathan Myers
You say that it is just an artifact of a failed theory. If that is true, then dark matter does not really exist. If you maintain that it is just an artifact, then you must have something upon which to base your claim. Please share the information which led you to that conclusion of fact.
If it is just opinion, fine, but then you need to rework your statement to “I think that dark matter is just an artifact of a theory that I believe has failed,” and no more questions will be raised, at least from me, regarding citations.
So far, your comments on the subject have not appeared to be merely opinions, but rather assertions of fact.
September 4th, 2008 at 2:45 pm
@ Todd W.
Click on my name, Todd W. The link will explain everything.
September 4th, 2008 at 4:14 pm
@Todd W: It is a fact that I know of no reason to think it exists. It is also a fact that I know of no reason to believe in ghosts and goblins. As to whether it indicates failure… I pull over and change my tire only when it’s gone flat. Your experience might differ.
September 4th, 2008 at 4:23 pm
@IVAN3MAN
Heh. Thanks for the link.
@Nathan Myers
How much have you studied the topic of dark matter? Have you read any studies?
September 4th, 2008 at 5:30 pm
@Todd W: Exactly which part of “ask somebody else” are you having trouble with?
September 4th, 2008 at 7:24 pm
@Nathan Myers
Ah. Seem to have touched a nerve. Apologies if my questions annoy you. Consider the matter dropped.
September 4th, 2008 at 8:32 pm
Todd W. Said on Sept. 4th, 2008 at 11:42 am
“@StevoR : Blue car with a green nose.”
There you go. I would’ve said the colour of the car was also just fractionally more green than blue although right on the border of both.
What do others here think – green / blue or both?
Incidentally folks, when I’ve printed bits of this thread out they’ve all
been in bold as well as italics. So somethiong else odd is going on with it as well …
Nathan Myers Said on September 4th, 2008 at 4:14 pm :
“@Todd W: It is a fact that I know of no reason to think it exists. It is also a fact that I know of no reason to believe in ghosts and goblins. As to whether it indicates failure… I pull over and change my tire only when it’s gone flat. Your experience might differ.”
Being pedantic in F1 races & other forms of motorsport they generally
change tryes before they go flat! Even in normal life when you’re tyres get bald and worn people often change them before waiting for the flat to
occur ..
Also while the reasons for believing in ghosts and goblins may be poor – anecdotal evidence, old stories and the like – reasons do exist, just not ones that would suffice to convince you. Not that I’m saying they do exist just that reasons -whether valid or spurious – for thinking they *might* exist do exist.
But like I said I’m being pedantic (& a bit humerous) here!
As for Dark Matter well that’s another (fairly dark & murky itself) topic for another thread methinks …
September 4th, 2008 at 9:30 pm
Trying to bring things back to the green stars /objects in space topic & Istillhaven’t had any response to the question :
Are B type stars = greenish as well as bluish white sometimes? (Turquoise or aquamarine in hue perhaps?)
We have after all a number of examples :
1) Zubenelgneubi – main genuinely green star candidate – B8 type hydrogen fusing dwarf.
2) Almach component star – also type B8 main-sequence (H -fusing) dwarf that appears green or green~ish although in a multiple star system & poss. contrast effect with K3 II bright orange giant.
3) Antares B – also a green or green~ish B class dwarf (B8?) but again in a multiple system & possible contrast effect with M1 Ia red supergiant –.
4) Rasalgethi B – also a B class dwarf (B8?) although again part of a multiple system & possible contrast effect with its M5 Ib red supergiant primary.
5) One of the stars in the Jewel box cluster mentioned in the other thread I think also a B-type star perhaps although I’m not too sure.
So could there be something to this B type green or green~ish stars thing and could the greenness of the Antares and Rasalgethi companions be at least partly intrinsic as well as contrast? Of coyurse there arealso counter-examples of many non-Green B-type stars but still ..
Also could the secular (historical times) variability, the apparent fade in Zubeneschmali’s brightness be connected with its greenness?
One idea : could Beta Librae – Zubeneschmali’s – fade be connected with the ejection of a cloud of gas (a super-sized Coronal Mass Ejection type event perhaps?) which has created a surrounding gas cloud that has transformed the star from sapphire to emerald in colour?
What do y’all think?
September 4th, 2008 at 10:11 pm
StevoR:
See the link “Color Optical Illusions” I posted above at 8:29 am, 4th Sept. 2008.
Also, you should’ve written your tyres not “you’re” tyres.
September 6th, 2008 at 1:17 am
@Todd W: I was beginning to think you were a bad Perl script.
September 6th, 2008 at 7:58 pm
@Nathan Myers
Nope. Just incredibly persistent. My requests for literature and other evidence to further my own understanding of a subject have a tendency to rub certain people the wrong way.
September 6th, 2008 at 10:45 pm
@Todd W: This blog isn’t really the sort of place to learn much of anything. Tell you what, from now on I’ll link my name (as above) to places that are better. I’m afraid there will be a bias toward biology, perhaps because biologists seem to be more aware of what’s amazing than in other fields, or just because more that is biological is amazing. Don’t expect to get any work done if you start following them.
September 13th, 2008 at 7:11 am
I’ve been reading some (more) of Nathan Myers’ posts/comments, in response to Phil Plait’s blogs … wow, just wow.
Aside from the weaving and dodging, and aside from the specific content, I get the impression that, in NM’s view, astronomy is not a science and cannot be one … ever (exception: once probes visit something that was once solely the domain of astronomy, such as the Moon, remote observation can be supplemented by in situ research).
Would you care to say a few words, NM, on what you regard the criteria for assessing whether some piece of astronomical research is scientific or not are?
Back to plasmas, gas, fluid dynamics, etc.
The Sun is a big ball of plasma; to what extent, Nathan, is any study of the Sun unscientific if it does not explicitly and directly incorporate plasma fluid dynamics?
Specifically, are all the papers on the Sun and neutrino physics unscientific for not having explicitly incorporated PFD?
December 29th, 2008 at 11:33 am
This is an ancient issue by now, but just for the record, here’s the Ed Mitchell/UFO/Michael Horn post with 1101 (and counting) comments:
http://blogs.discovermagazine.com/badastronomy/2008/07/30/followup-ed-mitchell-and-ufo-believers/
Some folks above said the comments were missing.
December 29th, 2008 at 11:55 am
Hmm… the web-master still hasn’t fixed the rogue italics on this thread. So, it’s up to me, then…
December 29th, 2008 at 11:56 am
VOILÀ!
August 6th, 2009 at 2:43 pm
Well done IVAN3MAN – belatedly.