Someday, Mars will stop surprising me.

Today is not that day.

The image below was taken by the HiRISE camera on the Mars Reconnaissance Orbiter, which has been taking devastatingly high-res pictures of the Red Planet for many years. While passing over the edge of the Tharsis Shield — a huge uplifted region of Mars home to its four gigantic volcanoes –it saw this bizarre fieldof craters:

[Click to hephaestenate.]

First, you may think these are mounds and not craters, but that’s an illusion. Our brain uses illumination to gauge up and down in pictures like these, and assumes the sunlight is coming from above. However, these really are craters, but the illumination is coming from below — north is roughly toward the top of the picture and the crater field is at a northern latitude of about 50°. Flip the picture over if it helps (I’ll be honest, even doing that makes it hard for me to see these as other than mounds; confounded brain!). You can see more examples of this illusion here, here, and here.

But that’s not the weirdest thing about these craters. What’s really odd is they aren’t circular! Impacts are generally round unless 1) the impact is at a very shallow angle, b) the terrain suddenly goes from one kind of material to another, creating a discontinuity, or γ) something happened after the crater was formed to distort it.

A shallow-angle impact is almost certainly not the case here, since there are so many craters spread out over the region that an incoming object would’ve had to break up into a gazillion pieces, all of which came in at that angle. Not impossible, but it seems unlikely.

The changing terrain idea doesn’t work, since again the craters are spread out over the area. You might see one crater with a sudden break in its rim or change in shape, but dozens? Spread out in all directions? Nope.

That leaves after effects, and in this case we have two more clues. (more…)

As a change of pace, I was the guest rogue on this week’s episode of The Skeptics’ Guide to the Universe. We covered a lot of ground, from Futurama heads to asteroid mining to Mayans… and I have an abysmal record at the Science or Fiction segment when I’m on the show, so you can hold your breath in anticipation to see if I finally get one right, or once again go down in flames. I’ll note, obviously, that I always get it right when I listen to the show at home.

And nothing says love like Rebecca promising she’d freeze my head. Such a romantic.

Science Getaways is a company my wife and I started so that science enthusiasts (and you better face it, since you’re reading this, that’s you) can go on a vacation that has extra science added. For me, science isn’t a career or a hobby — it’s a lifestyle. I can’t get enough, even on vacation, so we figured why not put together vacation deals that have bonus value-added science?

The first Getaway is September 16 – 20 of this year, and it’ll be at the C Lazy U ranch, an all-inclusive luxury ranch in the Rocky Mountains. We visited there last year and it’s incredibly beautiful. The views are spectacular, and you’re really out in the middle of nature there.

Which brings up a funny coincidence. This morning I was going through some photos I took, and stumbled on one I took last year when I was up in Rocky Mountain National Park filming a science documentary. When we finished shooting we packed up the gear and headed down the path to the van. As we made that long walk, I looked over to my right and was pretty surprised to see this:

About two dozen elk were just standing or sitting around, casually watching us and other hikers as we stumbled down the path! It was astonishing; they were very calm and satisfied to just watch us walk by, although the male — that’s him with the antlers — was eyeballing us to make sure we didn’t get too close to his harem. He didn’t have to worry. I was too busy trying not to kill myself carrying the big camera tripod over my shoulder; wandering off the path to get a closer look at his wives wasn’t really on my mind.

As I looked at the picture of the elk I started thinking about seeing more of them now that the weather is warmer and we start weekend hiking in the Rockies again. That’s when I thought about Science Getaways — the ranch hands told us that in late summer it’s common for herds of elk to walk across the ranch grounds. Elk are big — like horse-sized deer — so that must be quite a sight (check out these photos of elk at the ranch in the winter). And that’s not all we’re likely to see; there are mule deer, pronghorn, eagles, and more — maybe even moose. Biologist Dave Armstrong will be with us to point all that out and tell us about what we’re experiencing, too.

I’m really looking forward to the nature hikes. That area of the Rockies is surpassingly beautiful (you don’t have to take my word for it; here’s a family who wrote up their experiences at the ranch). Of course, once the Sun goes down, the reins of science will be passed from biology to astronomy. I think of all the things about this, that’s what I’m most excited about: clear, dark, crisp skies, and unfettered access to telescopes! I’m bringing my Celestron 8", and there will be other ‘scopes there too. The views will be amazing, whether you’re looking out over the mountains, or up over the mountains!

If you’re interested, take a look at the site we’ve set up for Science Getaways. Also, my friend Maria at Skepchick interviewed me about this, too. If you have questions please drop us a line!

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 am very happy to see a very unwelcome visitor go away: La Niña is dead.

Over time, the pattern of ocean and atmospheric circulation changes. When cooler water in the eastern Pacific Ocean is brought to the surface at the Equator, it’s called La Niña, and when that water is warmer it’s El Niño. This changes the way winds blow and water evaporates, and during La Niña Australia gets torrential rains and floods, while the US gets drought conditions, especially in the southwest.

This year, the jet stream was also held up near the US/Canada border, so the winter was very mild, and many states suffered severely dry conditions. But finally, after two years, equatorial waters are warming up. As you can see in the image above, the water near the Equator was cooler (blue) in January 2012, and now a stream of warmer water (red) has appeared north of it. This means neutral conditions will take hold (and eventually lead to an El Niño).

All winter here in Boulder it’s been far warmer and drier than usual, and in my travels these past few months the story has been the same nearly everywhere. The mountains to my west have been nearly free of snow, something I haven’t seen since moving here. But literally, as I type this it’s raining steadily outside, again something I haven’t seen in many months.

It’s very welcome! Well, I’m rather hoping it doesn’t interfere with the talk and star party I’m doing in Boulder this coming Saturday, but in the meantime it’ll be nice to see the creeks rising, the snow pack increasing, and the trees looking a little bit peppier.

Image credit: NASA Earth Observatory/Jesse Allen and Kevin Ward, using JASON-2 data provided by Akiko Kayashi, NASA/JPL Ocean Topography Team.

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.

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…)