Blogs / Bad Astronomy

My friend, the magician Andrew Mayne, is here at Carl Sagan Day, and told me that he will be live streaming the entire event on UStream! I’ve embedded the video viewer below (hopefully it won’t start playing automatically). If you go to the UStream page Andrew set up there’s a chat room where you can talk to fellow astronomy and space enthusiasts too.

The event starts at noon Eastern time (17:00 GMT) , so those of you not here in person in Florida can still watch, and even virtually participate in this inaugural festival to celebrate Carl Sagan!

A quick reminder: the Carl Sagan Day celebration will be at Broward College in southern Florida on Saturday! Speakers include James Randi, Jeffrey Bennett, David Morrison, and me. There will be lots of stuff for kids and astronomy enthusiasts of all ages. Check my blog post from Monday for more info.

Also, there will be a reception that night at 8:00 p.m. as well. Requested donation is $10. I hope to see some BABloggees there!

The hi-res Lunar Reconnaissance Orbiter’s camera captured a pretty cool image of a (what I’m guessing is an ancient) landslide on the Moon. Check this out:

[Click to embrobdingnangate.]

The slide is down the steep slope of a crater called Marius, located in Oceanus Procellarum, a vast smooth-surfaced area on the Moon (generally called "maria" — singular is "mare" — and easily visible to the naked eye). The crater itself is pretty old; the floor is covered with the same smooth surface as the mare around it, so it predates Oceanus Procellarum which we know is pretty frakkin’ old.

The slide is very interesting; what could have caused it? A moonquake, or a nearby impact? Either way, the ground shook, knocking loose rubble at the crater rim which then rolled downhill. And just to give you an idea of the scale here, the image is 510 meters across: you could walk that distance in a few minutes. The fingers of debris are only a few dozen meters across at most! The smallest objects you can see in this image are less than a meter across.

Features like this on the Moon yield a lot of information. Better, as the LROC page notes, this feature can be compared to similar ones on Mars, giving scientists insight into both worlds.

And? It’s just really cool. Landslides on the Moon! Look out below!

If you’re jonesing for some spacey stuff and maybe some critical thinking too, then check out these three links:

1) Starts with a Bang has a diary of the Ares I-X launch a couple of weeks ago.

2) The 127th Carnival of Space is lying in wait at Next Big Future.

3) The 123rd Skeptics Circle is at Blue Genes Science News, where things have become decidedly Galilean.

So go waste your Thursday afternoon learning stuff.

Ever since the Hubble upgrade a few months ago I’ve been waiting to see the results of it getting back to routine science observations… especially for the new Wide Field Camera 3, which promised to return gorgeous imagery.

Well, the wait’s over. The first image is out, and it’s a nice one: star formation in the spiral arm nurseries of the nearby galaxy M83:

[You know the deal: click it to embiggen, or go here to grab a delicious 15 Mb 3900x3900 pixel version.]

M83 is about 15 million light years away, making it practically a next door neighbor for the Milky Way, as well as a tempting target for telescopes. Proximity = clarity in most cases, and with M83 we have a great view of its lovely spiral arms. This new image from Hubble’s WFC3 shows unprecedented detail, too. There are star clusters everywhere, factories cranking out baby stars by the millions. There are also something like 60 supernova remnants, the expanding gaseous debris from exploded stars, five times the number previously seen in this galaxy.

The colors are interesting. This picture is not quite true color. Sure, blue is blue, green is green, and red is red, but they also added a second version of red coming from the light of warm hydrogen gas (called Hα in astronomical parlance) as well as a fifth color: cyan (turquoise) coming from the light of warm, tenuous oxygen. That light is typically emitted from gas clouds making stars as well as the gas emitted from stars when they die (in fact, my PhD thesis was based on observations of this oxygen-light glowing from a ring of gas around an exploded star). You can see that this teal-like glow pervades the entire image: oxygen is everywhere! But it’s so thin it’s more like a hard laboratory vacuum than anything you could breathe.

Also, if you look closely at the pockets of red clumpy gas, you can some that are edge-brightened, like a soap bubble. These are where stars are being born in vast numbers. Their mighty winds expand outwards, carving huge cavities in the gas. My favorite is the one in the middle left of the image, zoomed in here for your viewing awesomeness. The stars are so closely packed they blur together, and each that you can see here would dwarf the Sun in mass, size, and brightness. You can also see that the rim of the bubble is more pronounced below the star cluster, which means that the surrounding gas in the environment of the cluster is thicker there, and has piled up more as the expanding winds have snowplowed it.

And everywhere in this picture are the dark ribbons and filaments of dust, dust, dust. These are long molecules (usually with lots of carbon) which are created by new stars and dying stars. They litter galaxies like M83 as well as our own. And while they make life difficult for optical astronomers who struggle to penetrate the thick veil and see what lies beneath, the dust is interesting all by itself… and adds a certain depth and grace to images like this one.

And, on the right of the big image, is the white glow of the galaxy’s nucleus. You can see detail of the dust, stars, and gas all the way down to the very center. It’s an amazing image, and I’m sure will keep astronomers busy for a long, long time.

What a great start to the return of the Hubble! And, as always, I can’t wait to see what’s next.

Speaking of HiRISE and Mars…

The Phoenix Mars Lander is sitting at the Martian north pole, its mission complete. Designed to study the history of water on Mars and investigate potential human habitability, it touched down in May 2008. It dug trenches and examined the surface soil of Mars for months, but the Martian winter was inexorable. Eventually, the intense cold forced engineers to shut Phoenix down (as planned), and there it still sits.

The HiRISE camera on the Mars Reconnaissance Orbiter took images of Phoenix last year while its mission was still active, in June 2008. Here’s that image:

Phoenix is pretty obvious! The surface there was relatively free of frost at that time. But scientists on Earth decided to get more images, this time during the winter. In July of this year they found Phoenix once again, but the picture is a little different!

First off, the green is not real; this is a false color image. So don’t go thinking they found moss bogs or anything like that. What you’re seeing is the same field as in the first picture, but this time its covered with carbon dioxide frost! Even Phoenix appears to have CO₂ over it, making it pretty difficult to see. I imagine that if they hadn’t taken the earlier picture, it would’ve been a lot harder to pick the lander out from the background.

Spring sprung on the northern hemisphere of Mars a couple of weeks ago, and in another few months scientists will try to contact Phoenix and see if they can wake it up after its lengthy hibernation. It’s a bit of a long shot — the mission wasn’t designed for it — but one thing we’ve learned about the probes we’ve sent to Mars is that they can be incredibly hardy: the two rovers are still operating years after the initial design lifetime. So maybe Phoenix will live again, and get back to work (expect other news sources to say it will rise from its ashes; a bad metaphor given that it’s covered in frost). And if it does, images like the ones above from HiRISE will help us back here on Earth interpret what it’s seeing. The more eyes we have on Mars, the better.

Mars is weird. It’s small, and cold, and has a thin atmosphere that’s almost entirely carbon dioxide, and what isn’t CO₂ is nitrogen and, bizarrely, argon.

So you expect to see weird landscapes. But even so, Mars has the potential to be really, really weird. Check this out:

That slightly disturbing image (click to embiggen) is not a microscopic picture of a scientist’s colon (at least, not as far as you know). It’s actually a region near the Martian south pole. It was taken with the HiRISE camera on the Mars Reconnaissance Orbiter, and the area shown is roughly 700 meters across (about 0.4 miles).

What you’re seeing are layers of the polar ice cap. The ice is mostly CO₂. Mars is so cold that a lot of the cap persists throughout the year, and is called the residual cap. Some of it does sublimate, though, which means it goes right from a solid to a gas. Underneath that layer is something more solid, perhaps water ice, that does not sublimate. As the upper layer partially goes away, it leaves these weird Swiss-cheese-like patterns, revealing the smooth layer below.

This image only shows a small portion of a much larger area where this occurs. Here’s the "context image", a zoom out if you will:

I marked the rough outline of the zoomed image in this one (it’s rotated about 90 degrees counterclockwise in the zoom). You can see that this odd terrain (aresain?) goes on for kilometers. It really does look like some sort of bacterial colony. But it’s actually the result of millennia, maybe millions of years, of constant annual atmospheric deposition and sublimation.

And just as a reminder — because I love to point this out — Mars was 250 million kilometers (150 million miles) away from Earth on August 20, 2009, when this image was obtained. Yet MRO was only 250 km above its target, yielding this fine imagery at a resolution of 25 centimeters (10 inches) per pixel. Got a ruler handy? Pick it up, hold it in your hand, and think on the fact that we have spacecraft orbiting Mars, an alien world, that can take pictures of objects on its surface about the size of that ruler.

Man. I love this stuff.

[P.S. If you like this image, the HiRISE page has wallpaper versions of it; the links are at the lower right at that link.]