Since the first planet was discovered orbiting another Sun-like star in 1995, nearly 800 more have been discovered. Only a handful have been directly detected: most are discovered by their influence on their star, either by tugging it or blocking its light as the planet orbits (at the bottom of this post is a gallery of images of exoplanets detected in these ways). But some have been directly seen: either glowing by their own light, reflecting that of their star, or — ironically — seen when they’re not seen.

Say what? OK, this takes a sec to explain, but it’s cool.

The star 55 Cancri hosts at least 5 planets. Located 40 light years away, it’s one of the closer planetary systems, and has been intensely studied. One of the planets, 55 Cancri e, is bizarre: it’s twice the diameter of the Earth and has 8 times our mass. It’s thought to have a dense core surrounded by water… but Earth-like it ain’t. It orbits its star in a very tight orbit, circling it once every 18 hours. It’s so close to the star that the surface temperature is probably around 2700°C — or 4900°F! That’s hot enough to melt lead.

So yikes. If it does have water, it’s in the form of a weird super-heated steam only held to the planet due to its strong gravity. Even then, the atmosphere may be boiling away like a gigantic comet. So again, this isn’t like Earth at all. Even Venus isn’t this unpleasant, and on Venus it rains sulfuric acid.

Anyway, an object at that temperature will glow in the infrared, quite strongly. If it were sitting all by itself in space, it would be easy to see. However, it’s sitting next to a star which is millions of times brighter, making it a significantly more difficult target.

… but not impossible. (more…)

I realized today that I have never really directly promoted Felicia Day’s new YouTube Channel, Geek and Sundry. If you don’t know who Felicia is, then a) what are you doing on the internet, and 2) seriously, what are you doing on the internet?

Felicia is an actor, producer, writer, funny person, dork, and all-around cool person. I can’t remember if I first saw her on Doctor Horrible, where she played Penny, or on The Guild, a massively (and deservedly so) successful web comedy series she essentially created herself out of thin air (well, with the awesometastic Kim Evey too, hi Kim! [waves]).

She decided that spending 23.9 hours per day working wasn’t enough, so she started up Geek and Sundry to highlight geek stuff. The channel has several shows on it, including the on-air book club Sword and Laser, and Wil Wheaton’s gaming show Table Top. She has her own short show called The Flog, where honestly it’s just her being adorable, which is apparently in her DNA. I’ve been watching them and they’re great… so imagine my surprise when I got to the 46 second mark of this week’s episode:

Oh my. No humorously false braggadocio here, folks: that’s just plain cool.

Thanks Felicia!

You know why astronomy is cool? Because of things like this:

Galaxy clusters are collections of galaxies held together by their own gravity. We see clusters all over the place, and they’re among the largest structures in the Universe. We can find them at large distances, which means we see them as they (and the Universe) were young — it takes light a long time to travel across the cosmos. Astronomers went looking to find extremely distant clusters of galaxies, and found one at a staggering distance: 12.7 billion light years away!

Here’s an image showing the central part of the cluster:

[Click to bigbangenate.]

Each of those circled red dots is a young galaxy, so distant that the light has been on its way here for more than 90% of the current age of the Universe! And they’re almost lost among all those other stars and galaxies in the image (though their intense red color helps… as to why they’re red, read on).

Finding this cluster was a magnificent achievement. The astronomers used the massive 8.2 meter Subaru telescope to look at large swaths of the sky. They looked at the colors of the galaxies they found (PDF); distant objects would be so far away their light is significantly redshifted by the expansion of the Universe itself (I explain how this works here and here).

Galaxies are distributed throughout space, so you expect to see them scattered across the sky as well as in redshift (distance). When looking at one part of the sky, however, they found an unusually high concentration of galaxies that were very red. Using a different camera on Subaru, they took spectra of those galaxies — breaking the light up into very fine divisions of colors, like a rainbow with hundreds of colors in it — to accurately measure the redshifts of those galaxies. Spectroscopy of objects that faint is no easy task, but Subaru is a big ‘scope, and collect a lot of light even from faint objects at the remote reaches of the Universe,

The astronomers confirmed that many of the galaxies in their sample were at the same redshift (z = 6 for those in the know — which is a mighty big redshift). The odds of these galaxies all being at the same distance happening by chance is extremely small: only about one in a billion! So it’s pretty clear these galaxies really are physically associated with each other.

That is, clustered together.

This makes the cluster the most distant ever found that has been confirmed spectroscopically — one other has been found that might be farther away, but it hasn’t been confirmed yet. At 12.7 billion light years away, that means we see this cluster as it was a mere one billion years after the Universe itself formed! That provides key information about conditions in the early Universe, which are critical to understanding how it formed and changed as it aged.

The cluster itself is vast — it’s something like 50 million light years across. The team of astronomers used various methods to determine its mass, and their best guess is that its total mass is several thousand times the mass of our entire Milky Way galaxy! The estimation methods they used are fairly fuzzy, so it’s not clear how accurate this number really is. Still, the cluster is clearly huge, and massive. If we could see it today, it would probably rank among the largest structures in the Universe.

That’s not terribly surprising, if you think about it: only the biggest monster clusters can be seen at such a mind-crushing distance. The smaller ones will be harder to detect, so we’re likely to find the biggest.

Still, holy cow. I have read and written about extremely distant objects many, many times over the years, and have no doubt: I get chills every single time I think about this stuff. It wasn’t that long ago when the entire human race couldn’t be bothered to look beyond the tip of its collective nose. Now we can look into the fires of the Universe’s birth, into that forge itself, and tease out the secrets of how we came to be.

That’s why astronomy is cool.

Hmmmm… the astronomer in today’s xkcd comic looks familiar, even as a stick figure.

At least he didn’t draw me as a zombie. But I’m no Feynman.

And hey, together with SMBC I think this makes me king of the four-letter comics. I mean, um. Well.

[N.B. And yes, it really is me, I got word from The Man himself. Funny how a minimalist drawing with some context invokes recognition; I've been getting notes from people all morning.]

So, tonight is the so-called Supermoon, when the Moon happens to be full at the same time it’s at perigee, the point in its orbit closest to the Earth. This makes it somewhat larger and brighter than normal, and that’s getting a lot of attention in the press. I pointed out a few days ago that in reality, you almost certainly won’t notice the difference between this full Moon and any other, mostly because the difference is small, and our eyes and brain are terrible at judging things like that without something to directly compare it to.

I was thinking about this last night as I watched the almost-full Moon rise in the east (which, I’ll add, ironically looked huge due to the Moon Illusion!), and thought of something that might help illustrate this last point.

Monetary eclipse

Imagine you go outside tonight to look at the full Supermoon rising in the east. Imagine also you’re holding a US dime in your hand (if you live in another country, feel free to substitute your local currency, but beware of the math; hang on a minute to see).

Let me ask you this: How far away would you have to hold the dime so that it appears as big as the Moon to you?

A few inches? A foot? (Convert to metric if you wish). Go ahead, guess!

… OK, ready? [Answer is below the fold so as not to spoil it.]

(more…)

Messier 106 is an elongated spiral galaxy, seen by us at a low angle, in the constellation of Canes Venatici (CANE-eez ven-AT-ih-sigh, the hunting dogs). It’s about 25 million light years away, give or take. That may sound far — 250 million trillion kilometers! — but for Hubble, that’s considered close. So if you take a stack of Hubble images of M106 and put them together, as amateur astronomer Andre vd Hoeven did, you get a lovely picture it!

[Click to galactinate and get access to a zoomable version -- and you want to. I shrank the image considerably to get it to fit here. (UPDATE: there's a HUGE version at Flickr.)]

M106 looks a bit odd to my eye. The overall structure is pretty typical for a two-armed spiral seen at this low angle, but still… those red spots mark the location of busy star formation. The hot young stars heat up their surrounding gas, and the hydrogen in them reacts by glowing. Usually you see star formation that intense over a large region of the galaxy, or a small region, but not somewhere in between like this.

Not being familiar with the galaxy, I looked it up, and found the image inset here (which I’ve rotated to better match the Hubble image above). Right away we see something really weird: there are two more arms invisible in the Hubble shot!

What the what?

The inset picture is a combination from a lot of telescopes and wavelengths: visible light (displayed as gold), infrared (red), radio (purple) and X-ray (blue). The visible and IR line up well with Hubble’s view, but the radio and X-ray clearly show those extra arms. X-rays are emitted by very hot gas — like, million degrees hot — and radio is emitted by gas with a strong magnetic field permeating it. That’s a hint about what’s going on. Another is that the core of the galaxy is very bright, glowing more fiercely than you’d expect from a normal galaxy.

(more…)

I don’t think I need to tell you much about this. Set it to the highest resolution, make it full screen, sit back, and watch this NASA promotional video called "Pursuit of Light".

[A huge 3420 x 1152 pixel version is available for download as well.]

Most of the images shown have graced this blog over the past few months, and you can find various descriptions of them with details if you search.

But that’s not the point of this video. It’s to inspire: wonder, awe, beauty, majesty, curiosity, and imagination.

So, a note to NASA: YES. This is how you do it. Well done.