Three views to a comet

By Phil Plait | October 8, 2010 7:00 am

103P/Hartley 2 is the somewhat prosaic name for a pretty nice comet in our skies right now. It’s still a little bit too faint to see without aid of binoculars or a telescope, but it’s getting brighter: on October 20th it’ll pass by the Earth at a distance of a mere 18 million km (11 million miles)!

Astronomers all over the planet are jumping at a chance to see a comet up close… and the views they’re getting are really, really cool. Behold!

wise_hartley2

That’s Hartley 2 as seen by WISE, an orbiting NASA mission designed to survey the sky in the infrared, so it’s very sensitive to objects that astronomers consider warm — that is, a few degrees above absolute zero! It’s seen comets before, since they fit the warm-to-astronomers-but-freezing-to-anyone-else category.

Mind you, the actual solid part of the comet is only a few kilometers across, far smaller than a single pixel in this picture. But it’s loaded with frozen ices which turn into gas as the comet nears the Sun, enshrouding the nucleus with fuzz, and streaming behind it as that long, long tail. In this picture, the tail is nearly 2 million kilometers in extent — well over a million miles!

hst_hartley2What I think is funny is what sometimes happens when you try to zoom in on the head of the comet: you get a fuzzy picture like this one. It’s hard to see detail in a comet, and sometimes when you use more magnification this is all you get. It may surprise you to find out this is a photo from the Hubble Space Telescope!

Even though it looks blurry, this is actually a very important picture. In a few weeks, the NASA mission EPOXI — what used to be called Deep Impact, but has now been re-purposed to look at planets around other stars and objects in our own solar system — will be passing near the comet, and images like this will help astronomers get a better understanding of how the comet is behaving (as well as more accurate positions for the comet over time). Also, this image does allow astronomers to estimate the size of the comet’s solid nucleus: it’s about 1.5 km (0.9 miles) across. That’s fair-to-middlin’ as these things go.

Also, sometimes comets emit jets of gas from frozen pockets on their surface. This can spin the comet up, and also sculpt amazing spiral patterns… and create hazards for any passing spacecraft. Hubble’s image doesn’t show any jets here, but had they been there they’d have been spotted. The fact that the comet looks relatively featureless is actually a good thing!

This all reminds me of a time in grad school when a bright comet was well-positioned to see from where I was. I remember looking at it through binoculars and it was spectacular! I was excited to look through a big telescope, figuring it would be a jaw-dropping view. But when I got to the eyepiece, it looked like I was examining a Q-tip with a magnifying glass. Sometimes, the long view is prettier.

Hartley-2-at-CasWith Hartley 2, you can get your own chance to see it! It’s currently high in the northern sky just south of the constellation of Cassiopeia, which is easy to spot as a giant W in the northeast once the sky gets dark after sunset. Hartley 2 is still faint, and there are lots of things to see in that region of sky, so it’ll be a bit tough if you’re not familiar with the area. Helpfully, Sky and Telescope magazine has a great finder chart online. They also have descriptions of it and where it’ll be for the next few weeks. But right now the Moon is new, and so the skies will be darker: so if you have binoculars and a dark site, now is the time to look.

And if you can’t find it, that’s OK: stay outside, and scan the heavens with your binoculars. Jupiter is up, for example, and there’s so much to see! A night spent under the stars is never wasted.

Image credits: NASA/JPL-Caltech/UCLA, NASA, ESA, H. Weaver (The Johns Hopkins University/Applied Physics Lab), Sky and Telescope

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (30)

  1. The only comet I’ve ever seen is Hale-Bopp. It was clearly visible to the naked eye, and was gorgeous. I stared at it from horizon to horizon. *chills*

  2. Wendy

    Off topic – will you be in Boulder on 10/20 to confront Wakefield? Figure that’s your home turf, and a passionate cause…

  3. I’ll have to try to bag this one tonight at the Fan Mountain Open House. I can put it and the Double Cluster in a single eyepiece, perhaps!
    Thanks!

  4. veebs

    I saw it last night in my 10X50 binoculars. Still fairly faint and diffused, but still a great sight with the Double Cluster in the same view.

  5. Awesome Phil, can’t wait for the 20th!

    ~Rhaco

  6. Brian York

    Now, given how close it’s passing, imagine trying to do bright object screening for 103P (especially because it’s passing close enough that you have to worry about parallax differences depending on where HST is in its orbit), whilst constantly getting given new observing windows to check….

  7. AstroPaul

    Now let’s not exaggerate — WISE’s 22-micron band is most sensitive to blackbodies at 131K. Sure, that’s COLD, but it’s roughly the temperature of Jupiter’s “surface”. It’s no 3K cosmic background, that’s for sure! Nice and toasty!

  8. dcsohl

    I’ll be out trying to spot Hartley… but I have to say, I think I’m permanently spoiled by Comet Hyakutake. Comets are still very cool and all, but nothing will ever even come close to that…

  9. Michel

    I´m still trying to catch a glims of Hartley.

    And off topic:
    “Conspiracy theorists confident Photoshopped NASA image is a cover-up ”
    news.com.au/technology/conspiracy-theorists-confident-photoshopped-nasa-image-is-a-cover-up/story-e6frfro0-1225936084529

    hrrmppfff

  10. Grand Lunar

    I think Hale-Bopp was my first comet that I clearly saw, although I have vague memories of Halley.
    There was that one bright comet a few years ago, but I forgot it’s name.

    Anyway, hope I can spot this one!

  11. Just as long as nobody uses this comet to predict the end of the world (sigh).

    http://drvitelli.typepad.com/providentia/2010/08/comet-crazy.html

  12. Messier Tidy Upper

    I see you’ve made a WISE choice of topic here, BA. ;-)

    Great pictures & write-up. :-)

    it’ll pass by the Earth at a distance of a mere 18 million km (11 million miles)!

    What’s that in Astronomical Units?
    (Yeah, should calculate it myself I guess but then I’m two-thirds asleep now & my maths skill, alas, sucks at the best of times.)

    you can get your own chance to see it!

    Sadly, I know I won’t be able to see Comet Hartley 2 – at least not until its moved a fair way from where it is now – its circumpolar for the northern hemisphere but totally out of view here in the southern – just like the rest of Cassiopeia. We’re not all northern hemispherers y’know. :-(

    @10. Grand Lunar :

    There was that one bright comet a few years ago, but I forgot it’s name.

    Hyakutake was a great comet that went by just before Hale-Bopp was that the one you meant?

    Or could it be one that broke up a year or so ago named, I think, dubious on the accuracy of the spelling here but, Schwassman-Wachman (number? 3? 9?) or something like that?

    Or the best comet I’ve seen in my life which was McNaught’s comet last year – or is that already the year before now?

    (Hyakutake would rank second for me and then Hale-Bopp.)

  13. Given that Hartley 2 has a perigee (closest approach to Earth) of 0.12 AU ( 1astronomical units = 150 million km) and it has a diameter of 1.5 km, and Hyakutake on the other hand had a perigee of 0.1 AU and a diameter of 2 km – is there reason to expect a similarly spectacular show – or is Hartley 2 not nearly as volatile?
    And what about the date of perigee? Outside the U.S. it is 20.10.2010 – a coincidence? I THINK NOT! /conspiracy off
    Grand Lunar @ 10: I believe you might be thinking of Comet McNaught of Jan. 2007. That was the worst case of bad timing for me: I lived in Australia, but it was visible in the Northern hemisphere first. and then I had to travel to the Northern hemisphere when it left the Northern skies for the Southern ones – I completely and utterly missed it. And then to rub it in, my pals a Mt. Stromlo E-mailed me their stunning pictures of it :-/
    I am not going to miss one, though. And it will be a birtday comet for me :-)
    Cheers, Regner

  14. We’ve been watching it all week long at the Mid Atlantic Star Party near Robbins, NC.
    We’ve tossed everything from Binox, 4″ Apos, to a 30″ dob – its just not a very impressive comet. No real detail or characteristics that make it interesting: no tail, no ion, just a fuzz ball.
    Last night with it sitting next to the Double Cluster was a very pretty view, and the 6″ Tak refractor with low power gave the best views.
    I’ll keep revisiting it with my 18″ Obsession, but as it stands now, unless its close to something interesting, it’ll just be meh…..

  15. Thameron

    Gosh! Golly!! Gee willikers!!!

    Now I appreciate the majesty and beauty of naked eye comets as much as the next guy, but seriously unless one is going to hit us and lead to an extinction level event I don’t think they warrant all those exclamation points. Many of them are just fuzzy dots in the sky. Hyping them just leads to disappointment as Halley’s was in 1986.

  16. Vex

    Enjoy your viewing Regner! It is also a birthday comet for myself. I turn a year older tomorrow :)

    I’m excited to have so much going on in the sky right now – I’m still enjoying seeing Jupiter and now have this to look forward to. My poor boyfriend now has one more thing to listen to me ramble on about. He doesn’t quite share my enthusiasm, unfortunately.

  17. Floyd

    I saw Comet Halley (which I think of as Mark Twain’s comet) from the Carlsbad Caverns Natl Park parking lot in New Mexico (very dark skies, lot lights were off), though I could only see the head of the comet, which was low in the sky, and could see no tail.

    I missed Hyakutake, as I wasn’t into amateur astronomy at the time.

    So far Hale-Bopp was the most impressive comet I’ve seen; My wife and I watched the comet for weeks during evening walks in Albuquerque.

    I’m looking forward to Hartley 2.

  18. Anchor

    Had a splendid and viscerally haunting gaze at the comet (with a diffuse and short but distinct tail!) nestled alongside the Double Cluster in Perseus with my trusty 11×80 binoculars last night under prime conditions. Coyotes howling in the distance echoing through the valley completed the palpable sensation there, under that magnificent band of the Milky Way galaxy from Cygnus to Orion, that “we ARE the aliens”.

    All beings begin ‘ignorantly alien’ to themselves and their universe. The acquisition of knowledge requires the hard work of learning about the universe one is surrounded by. We’re just one example that has emerged on one of innumerable worlds that no doubt have their own counterpart star clusters, comets and coyotes to howl out the message from the stars…the message available to all beings wherever they’ve evolved in the universe, that we all share the very same origin in space and time that can be contained within a thimble.

    It’s enough to raise the hairs and hackles to fullest extension, guaranteed. (On approach to Halloween, a rather nifty season for it).

    Those are the moments in observing – directly, ‘up close and immediately personal’ with the authentic reality – that no artificial entertainment medium or technology can possibly duplicate.

  19. Anchor

    BTW…Thameron #15? If you ever saw a Great comet under decent un-light-polluted skies you would eat your words. Halley in 1986 wasn’t spectacular, but I found it quite striking as seen from Joshua Tree National Park just south of Death Valley – yet nobody said it would be as well exhibited as it had been in its previous passage. SINCE then, however, Comet Hale-Bopp and Comet Hyakutake would, I absolutely positively guarantee, have knocked your socks off IF you had bothered to go to a dark site to observe them. They were, I assure you, nothing short of astonishing. Too bad you missed them. Perhaps your general pessimism prevented you from stepping outside on a clear night to see for yourself.

    Hartley 2 is just a little comet, a short-period comet, a mundane example to be sure. NOBODY SAYS OTHERWISE.

    It is also raising interest because EPOXI (formerly Deep Impact) will fly by it soon. It IS that appropriately exciting. OK bub?

    So, let me toss your dreck back in your direction, if I may: “Gosh! Golly Gee willikers!!! How CYNICAL can a body get who can’t find anything stimulating except maybe a firecracker going off inches from his ear and refrain from committing sui…”…um, never mind.

    It occurs to me that this sort of idiotic ennui is a spreading disease – spawning all sorts of denialists and folk who are so obsessed with ‘certainty’ they can’t even think straight enough to listen to or weigh fresh evidence.

    Oh, how your sort bogs the rest of us down.

  20. Ken

    Here’s a backyard view of Hartley 2, taken in light polluted skies outside Vancouver BC on Sept 29, when the comet was at magnitude 7.6:

    http://www.flickr.com/photos/suraky/5050456486/

    … 7.5 inch Maksutov Newtonian telescope. Canon T1i DSLR, 13 minutes total exposure in 30 second subs, stacked in Deepsky Stacker so that the stars are minimized.

  21. Chris Winter

    RE: #9 —

    “ALIEN conspiracy theorists are confident they’ve caught NASA in the act of covering up the fact we are not alone in the universe.”

    In other news, President Obama is suspected of concealing the fact that unemployment has dropped to 3.6 percent in the last month. And for unexplained reasons, Secretary of State Hillary Clinton did not mention on her return from the Middle East that following Israel’s removal of all its West Bank settlements, Palestine has agreed to end their long conflict.

  22. Chris Winter

    dcsohl wrote: “I’ll be out trying to spot Hartley… but I have to say, I think I’m permanently spoiled by Comet Hyakutake. Comets are still very cool and all, but nothing will ever even come close to that…”

    I feel the same way. When I stepped out the front door of the place I lived then, Hyakutake was hanging right in front of my eyes, so big and bright I didn’t need binoculars to observe it. :D

  23. Anchor

    Patience is rumored to be a virtue.

    There is also considerable talk over recorded history that nature delivers without needing to consult an audience on Earth in advance.

    If one subscribes to the instant gratification supplied by cultural monstrosities such as religious and other superstitious traditions or relies exclusively on the comparitively impotent ability of audio-visual technology to stroke one’s wonder-strings, one will never ever be satisfied with nature and the universe they inhabit.

    But noooo…reality is just not quick or SPECTACULAR enough for them, is it?

    There is no question that Hartley 2 is certainly NOT in the class of a Hyakutake or Hale-Bopp in terms of an idiotic requirement for it to rise to a comparable spectacle.

    The expectation that it ought to achieve newsworthiness is positively idiotic. Hartley 2 probably won’t even reach naked eye visibility, and even if it does reach the threshhold of naked eye visibility at near magnitude 7 let alone 6, SO WHAT? Casual observers of the sky would STILL never notice it. Neither would the same casual observers have noticed Hyakutake or any of the MANY DOZENS of other great comets documented within just the last few centuries. Most people don’t even notice a FULL MOON in the sky, for cryin’ out loud.

    All of the ridiculous denunciations determined to find some ‘fault’ in the expertise of professional and amateur observers on this thread fall prat on their faces, hilariously so. It would be humiliating to anyone who understands what’s going on, but it’s evident that some boneheads cannot locate any humility.

    Evidently they lack patience as much as they lack the will to look for themselves. It’s obvious they lack everything it takes to compose a knowledgable comment. Yet they are not lacking in the audacity to jump right in there and bothering everyone else with how spectacularly little they know.

  24. Anchor

    @ Ken #20 : Fine shot! Well done. That diffuse tail is very similar to what I could see in my binoculars on the night of October 7-8.

    Can’t wait to see photos while it passed near the Double Cluster!

  25. Anchor

    Messier Tidy Upper #12 Says: “Hyakutake would rank second for me and then Hale-Bopp.”

    How novel it is of you to venture an opinion…with more faces. Nice and tidy an opinion it is too, confined as it is to your location in the southern hemisphere.

    I would challenge that in reporting that Hyakutake sported a naked eye tail that stretched well over 120 degrees of the sky directly overhead. Under my dark skies, that comet blew away BOTH Hale-Bopp and McNaught. As bright as the nucleus of Hale-Bopp was, it just wasn’t as stunning an apparition in the sky as Hyakutake was. And McNaught in the northern hemisphere didn’t exhibit anywhere near a spectacle to either Hale-Bopp or Hyakutake.

    So if you’ve observed them ALL from the southern hemisphere, like in Australia, where McNaught indeed became a spectacular sight, your expressed opinion isn’t very helpful to observers who would contradict you in a heartbeat, especially considering many of us ‘up here’ have many collaborators we consult with the ‘down under’ all the time, and have an excellent idea of what we have observed in concert. Your opinion therefore rings rather hollow. As usual.

  26. Chet Twarog

    Comet McNaught, also known as the Great Comet of 2007 and given the designation
    C/2006 P1, is a non-periodic comet WAS the comet some were inquiring about–seen first in N Hemisphere than southern.
    Hale-Bopp would have to be the most awesome for me, so far!

  27. Ken

    Thanks Anchor!

    Regarding the best comet debate … I’m the same way over meteor showers. I watched the 2001 Leonid meteor storm, bundled up in a parka, lying in the middle of a road in the tiny town of Wells BC. Counted over a thousand in a couple hours, often saw 2 or 3 at once, so now common meteor showers don’t impress me so much.

    But I think Hyakutake was my favourite comet too, but at the time i was removed from astronomy somewhat and didnt pay as much attention as I should have. Growing up I was going to be an astronomer absolutely 100% in. Then in university I discovered that I can’t do math and physics, which is 97% of what astronomy is apparently … So I spent the next years looking down as a geologist.

    It was blogs like this one, Universe Today, and the Astronomy Cast podcast that sucked me back in, leading to my backyard telescope.

  28. I’ve spotted it several times over the past week with my 20 X 80 Binoculars. In the wide binocular field it is much more impressive. The last two nights were especially nice as it glided by the Double Cluster in Perseus. It has a very extended coma that covers probably as much sky as one of the clusters in the DC.

    There’s all kinds of good photos being posted on the Cloudy Nights forums. I, myself, got about 90 minutes worth of exposures through my 300mm lens last night that I’m in the process of post-processing.

    Yeah, it doesn’t have a huge tail, but it is going through a rich area of the northern Milky Way which affords some very nice binocular views.

  29. Messier Tidy Upper

    @25. Anchor Says:

    Messier Tidy Upper #12 Says: “Hyakutake would rank second for me and then Hale-Bopp.” How novel it is of you to venture an opinion…with more faces. Nice and tidy an opinion it is too, confined as it is to your location in the southern hemisphere.

    Glad you like it! ;-) :-P

    BTW. I’m not confined anywhere & have visited the northern hemisphere on occassion to stargaze there as well. (Japan & the United States if you’re wondering.) I do, however, live happily in the southern hemisphere as do many others incl. readers of this blog. :-)

    I would challenge that in reporting that Hyakutake sported a naked eye tail that stretched well over 120 degrees of the sky directly overhead. Under my dark skies, that comet blew away BOTH Hale-Bopp and McNaught. As bright as the nucleus of Hale-Bopp was, it just wasn’t as stunning an apparition in the sky as Hyakutake was. And McNaught in the northern hemisphere didn’t exhibit anywhere near a spectacle to either Hale-Bopp or Hyakutake.

    Pity you couldn’t have seen Comet McNaught from Goolwa in South Australia then. That was a sight to behold! It was even visible in twilight daylight over the Adelaide oval despite the powerful lights used for illuminating the cricket game playing at the time. :-) :-D

    So if you’ve observed them ALL from the southern hemisphere, like in Australia, where McNaught indeed became a spectacular sight, your expressed opinion isn’t very helpful to observers who would contradict you in a heartbeat,

    Well there are a lot of observers down under in the Southern hemisphere too y’know Anchor. :roll: :roll:

    When, I note that in my personal experience, McNaught was the best comet I personally have ever seen winning out over Hyakutake then how many observers exactly would “contradict me in a heartbeat” over this subjective question regarding my personal observations?! :roll:

    .. especially considering many of us ‘up here’ have many collaborators we consult with the ‘down under’ all the time, and have an excellent idea of what we have observed in concert. Your opinion therefore rings rather hollow. As usual.

    Well it does seem that you, Anchor, are being a jerk as usual. :roll: :-(

    FWIW I don’t care for your style and don’t find what you have to say helpful or worthwhile either. :-( :-P

  30. #29 MTU:
    Well said.

    #25 Anchor:
    While I agree with your put-down of the apathetic “Who cares?” attitude, your insulting of MTU, for daring to express his personal opinion, based on his personal experience, does indeed make you look stupid. Surely, the question of whether one comet was “better” than another is entirely a matter of opinion, and could be influenced by the conditions under which an individual observed each one, as well as the intrinsic properties of each comet.
    I live in the UK, and the best comet which I have personally seen was Hale-Bopp. That’s for the very simple reason that, regrettably, I never personally got to see Hyakutake! During most of its brief ( by definition ) close approach, I was plagued by bad weather, and hardly got a cloudless night – and even on the couple of nights which were clear ( one of them being the actual night of closest approach, IIRC ), it was badly placed. I live in a southern suburb of a fairly big city, which has pretty lousy light pollution; at the time of closest approach, the comet was low in the north, i.e. right above the city centre as seen from my home, and was literally lost in the bright orange mess! And on the couple of clear nights, commitments prevented me travelling to find a dark sky.
    ( I’ve used that experience as my prime example, when writing to the city council about light pollution. )
    Hale-Bopp, OTOH, was so bright that it could be seen with the naked eye through the worst light pollution. ( Though even then, most people didn’t bother to look. On one clear night, when I was outside my house with binoculars, a couple passing by asked me, “Where’s this comet, then?” I simply pointed to the sky, and said, “There!” Their jaws dropped – yet until that moment, they hadn’t noticed it! ) And as its apparition lasted longer, I was able to find the time to take my telescope to a dark sky location.
    So, even if you and a million other people might argue that hyakutake was better, that doesn’t alter the fact that Hale-Bopp was the best which I have personally observed.

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

ADVERTISEMENT

See More

ADVERTISEMENT
Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »