[Note: Every week I hold a live video chat on Google+ where I answer questions from readers. I call it Q&BA, and when I get a question that stands alone, I'll make it its own video. ]

A lot of people, it seems, have morbid thoughts about space. Why else would I get asked this so much: "What would happen to the human body exposed to the vacuum and cold of space?"

Of course, this sort of thing is depicted in scifi movies a lot, and people are curious about it. And even though the movies always get it wrong — you don’t explode, or freeze instantly — it does make folks wonder about it. And while the reality isn’t maybe as gooey as in the movies, it’s still pretty nasty.

I wrote about this in my review of the movie "Mission to Mars", as well as answering a question many years ago from a reader. And even though it’s an icky thing to think about, it does give me a chance to talk about heat transfer, which is pretty, um, cool.

Well, this is depressing: Fomalhaut b may not exist.

Fomalhaut is one of the brightest stars in the sky, and is only about 25 light years away — that’s close, on a cosmic scale. It’s young, not more than a few hundred million years old, and surrounded by a vast ring of dust, leftover from the formation of the star itself. The ring is about 20 billion km (12 billion miles) in radius, and has a sharp inner edge.

That last bit is important: the easiest way we know to make the inside edge that well-defined is if a planet is orbiting the star just inside the ring. Its gravity would draw in particles, sculpting what would otherwise be a fuzzy boundary into a clean-cut ring. Not only that, but the ring is off-center; again, that’s likely due to the gravitational influence of a planet.

In 2008, astronomers announced they had found that planet: it appeared in two different Hubble Space Telescope images (shown above; click to embiggen) separated by two years. During that time, it had moved a little bit, by just what you’d expect for a planet at that distance from the star. The news came out the same day as other planets were seen around a different star, and I, along with lots of other folks, made it a headline (see the gallery at the bottom of this post showing all the planets we’ve been able to detect directly in images). This was, after all the first direct detection of a planet orbiting a Sun-like star!

Except, maybe not so much. A new paper has come out (PDF) trying to see Fomalhaut b using the Spitzer Space Telescope. Spitzer is sensitive to infrared, where the planet is far brighter.

And what did they see? Nothing.

Dang.

This image is pretty damning for the existence of Fomalhaut b. It’s the Spitzer infrared observations of the star, with the star’s light carefully removed. On the left is the actual image, and on the right they artificially added a point of light calculated to be equal to what the planet would emit, in the same position the planet should be — that’s what Arrow 1 is pointing at. It should be one of the brightest things in the image (Arrow 2 points to an unrelated bright spot). And while it’s obvious on the right, nothing can be seen on the left, in the real image. In other words, the planet isn’t seen.

Dang again.

Looking over the paper, it’s clear the astronomers were very careful, and did a number of tests. There’s no known way to make a planet as bright as what was seen in the Hubble images yet invisible in the Spitzer images. If the planet were there, they should’ve seen it. Also, a recent study has shown that if the two images show the planet moving, it would be on an orbit that crosses the ring! That seems extremely unlikely, if not outright impossible. A planet that big and massive — more massive than Jupiter — would disrupt the ring in short order if it physically crossed it. That really does make it very, very likely this is not a planet^*.

So what is it? It’s probably a clump of dust orbiting the star, reflecting light from the star enough to show up in the Hubble images but not warm enough to show up in the infrared observations.

That’s too bad. If this is true — and it probably is — then that takes away one of the very few planets directly seen in telescopic observations. However, there are still plenty more, and those have been confirmed (again, see the gallery below). And that number will tend to increase as time goes on, even if every now and again it drops by one or two.

Hmph. I once wrote that destroying a planet is hard. Sometimes, all you need to do is try to observe it a different way, and poof! It’s gone.

And now I have to update that gallery, and all my previous pages about it too. Dang science. Always learning more stuff and changing what we thought we knew.

Image credit: Paul Kalas, U C Berkeley; NASA/Spitzer/Markus Janson et al.

^* I chatted with an astronomer friend of mine about this, and he agreed with the authors of this new study. "Overall," he wrote me, "it smells like fish.". I couldn’t help myself. I wrote him back: "Of course it does. Fomalhaut is the brightest star in Pisces!"

[Below is a gallery of exoplanets that have been directly imaged using telescopes on ground and in space. Click the thumbnail picture to get a bigger picture and more information, and scroll through the gallery using the left and right arrows.]

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A few years ago, I started doing a weekly video question-and-answer session I called "Q & BA". It was a series of short videos that were a lot of fun to make. Unfortunately, the overhead got to be too high — it took all day to edit them! — and I had to stop.

But now, Google+ has changed that: Hangouts On Air is a feature that allows me to go on camera and broadcast a live video chat session to an unlimited audience. I take questions via Twitter and G+, and it’s a lot of fun. It lasts about an hour, and I put the whole session on YouTube. But some of the answers stand alone, and it’s easy to extract them out, package ‘em up, and post ‘em by themselves.

So I’m very pleased to announce I’m starting the series again! The first Q&BA is a great question: "What’s the best way to get kids into science and skepticism?" — what better way to get the series going again? Enjoy.

I’ll be posting more of these, maybe even one per day as time allows. If you like them, please give them a thumbs-up on YouTube, and drop by the Q&BA Hangout when I do them live! I announce them on Twitter and G+, so follow me there and stay up-to-date. Also, I have an archive with links to all the videos. Thanks!

Photographer Alistair Chapman traveled to Tromso, Norway — 300 km north of the Arctic Circle — to capture video of the aurorae from the recent spate of solar storms. What he caught on camera is remarkable: shimmering, waving, dancing lights moving in real time!

[Make sure you set it to 720p; Chapman says higher-def footage is coming soon.]

That’s amazing. Aurorae video is generally done with time lapse to show the movement, which is usually slow. I’ve often wondered just how fast the movement really is; I always figured fluctuations in the solar particle density, speed, and magnetic fields would produce real-time changes in the lights, but I’d never seen anything like this! After a search of YouTube I actually found several more.

I know some people will think this is fake, and I had my skeptic hat on while watching it. Note that in most time lapse you can see the stars move; in this they don’t, indicating (unless it’s a complete fake) short periods of time during the filming. Given that, plus the existence of other video like it, I’m thinking this is real.

Mind you, the movement you’re seeing isn’t a physical motion. It’s not like solid curtains of material are flapping. The lights are caused by atoms in the upper atmosphere getting hit by subatomic particles blasted out by the Sun, caught by our Earth’s magnetic field, and funneled down into our air. These particles dump energy into the atoms, moving the electrons up in energy (called excitation). The electrons then jump back down, emitting light in the process (de-excitation). As I said in an earlier post, it’s like needing energy to jump up stairs, but releasing it as you jump down.

Different atoms have different energy levels for the electrons — think of it as more or less spacing vertically between steps in a staircase — so the energy emitted is different, resulting in different colors emitted. That’s why we see green, red, purple… they come mostly from oxygen and nitrogen in the air. So as the magnetic field fluctuates, the particles are sent shooting down in different places, giving the appearance of motion while the atoms themselves don’t move.

The physics is complex and interesting, but the beauty of these lights is, to use another term, magical. Not in the fantasy sense, but in the sense of the emotional response we have to them. They are simply breathtaking in these videos, and are a wonderful by-product of our tempestuous Sun.

Tip o’ the lens cap to sunspotter.

I have nothing to add to this, except to say it’s great, and I saw it because Brian Cox mentioned it on Twitter.

Oh yeah: one more thing; watch it in HD and full screen. Coooool.

Late in 2010, scientists participating in a NASA news conference dropped a bombshell: they had found evidence that bacteria in California’s Mono Lake were metabolizing arsenic and using it in their life processes.

This was huge news, since arsenic is toxic for carbon based life. If some forms of life evolved a way to process it, this would open up a whole new field of biochemistry!

However, almost immediately, the work came under attack. Biochemists accused the original team of not performing the research carefully (to put it delicately). Rosie Redfield, a microbiologist at the University of British Columbia in Vancouver, was particularly critical. She decided, in fact, to try to verify the original work, and set out to do so openly, writing up her progress on her blog.

And now, according to an article on Scientific American, she can confidently provide a "clear refutation" of the arsenic uptake in the organisms:

Their most striking claim was that arsenic had been incorporated into the backbone of DNA, and what we can say is that there is no arsenic in the DNA at all.

That’s a pretty clear statement! The original team, lead by Felisa Wolfe-Simon, has responded, saying they need to see a fully peer-reviewed paper before making up their minds.

I’ll note that emotions have run fairly high throughout this saga. Dr. Wolfe-Simon got a lot of attention, positive and negative, and the negative was pretty charged. I’m not surprised by the reactions of either side of this issue.

In the interest of full disclosure, when the press conference was aired, I wrote a pretty straight interpretation of it. As I wrote in a followup post, I am not a microbiologist, and I trust NASA at some level. This event shook that trust quite a bit, and I am now far less likely to take a claim at face value, even when it comes from a source like NASA.

Science is a balance of trust versus skepticism, even at the best of times. An extra layer is added when the media become involved; that impartiality which is always precarious can be sorely tested by the chance at media exposure.

That includes my desire to write about something particularly cool, of course, as well as the more fundamental results obtained from the scientific research itself.

I’m glad this news has come out, and I’ll be curious to see what happens next. Dr. Redfield will need to submit her team’s work to the peer review process. Assuming it survives, I have little doubt we’ll be hearing from Wolfe-Simon again as well. In the Scientific American article, Dr. Redfield is quoted as saying, "We’ve done our part. This is a clean demonstration [that the original positive findings were incorrect], and I see no point in spending any more time on this."

That may be true for her and her team’s work, though I have a suspicion more work will have to be done either by her or other teams to categorically rule out the arsenic. But either way, what I can be certain of is that we are not done hearing about this story just yet.

Tip o’ the phosphorus backbone to Jeffrey Sullivan on Google+.

This summer will be a little bit longer than usual. A tiny little bit: one second, to be precise. The world’s official time keepers are adding a single second to the clocks at the end of June. This "leap second" is needed to keep various time scales in synch. It’s a bit of a pain and won’t really affect people much, but if it weren’t done things would get messy eventually.

This gets a bit detailed — which is where the fun is! — but in short it goes like this. We have two systems to measure time: our everyday one which is based on the rotation of the Earth, and a fancy-schmancy scientific and precise one based on vibrations of atoms. The two systems aren’t quite in synch, though, since the Earth counts a day as a tiny bit longer than the atomic clocks say it is. So every now and again, to get them back together, we add a leap second on to the atomic clocks. That holds them back for one second, and then things are lined up once again.

There. Nice and simple. But that’s spackling over all the really cool details! If you want a little more info, you can read the US Naval Observatory’s press release on this (PDF).

If you want the gory details, then sit back, and let me borrow a second of your time.

Time after time

There are lots of ways of keeping time. The basic unit day is based on the physical rotation of the Earth, and year is how long it takes to go around the Sun. But we need finer units than those! So we decided long ago to divide the day into 24 hours, and those into 60 minutes each, and those into 60 seconds each. In that case, there are 86,400 seconds in a day. OK, easy enough.

For most of us, that is enough. But scientists are picky (or "anal" if you want to be technical) and like to be more precise than that. And the thing is, the Earth is a bit of a sloppy time keeper. Tidal effects from the Sun and Moon, for example, slow it a bit. Other effects come in as well, changing the rate of the Earth’s rotation.

To account for this, in 1956 the International Committee for Weights and Measures made a decision: we’ll base the length of the second on the year, not the day. In fact, we’ll take the year as it was in the year 1900 (a nice round number, so why not) and say that the length of the second is exactly 1/31,556,925.9747 of the year as measured at the beginning of January 1900^*.

OK, fine. Now scientists have their anal precise definition, normal people have calendars, and we’re all happy, right?

Right?

Sunrise, sunset

Yeah. Not so much. (more…)