Blogs / Bad Astronomy

I’ve been posting a lot about antiscience crackpots and the damage they do, and while it’s important, it gets irritating to have to do it. After the site Boing Boing has to post something atrocious, they post a unicorn story or picture to cleanse the brain’s palate.

So here is my version of a unicorn: a soothing picture of Saturn from Cassini.

This is another in the series of beautiful equinox images from Cassini, as the Sun shines straight along the rings. While the icy moon Enceladus is not in the picture itself, you can see its shadow just below the shadow of the rings on Saturn’s cloudtops. The moon you can see in the image, just below the rings, is Mimas.

So, take a deep breath… remember that reality is real… and that we can investigate it, examine it, learn from it, and drink deeply of its beauty.

Ahhhhhhhh. That’s better.

My brother-in-law is a pretty good photographer (as you may remember). He just posted this lovely picture of the waxing gibbous Moon tucked in amongst the clouds at sunset:

Click it to embiggen. It’s not hard to get nice shots of the Moon, even during the day, though to get one this nice it does take a bit of experience and work. But it’s not all that technically challenging, and since it’s IYA 2009 anyway, I encourage everyone to give it a try. The Moon is bright and easy to spot, making it the obvious target for a beginning attempt at astrophotography. But you’ll need a telephoto; the Moon is smaller in photographs than you might expect. Experiment! Play around! And if you get nice results, link to ‘em in the comments. Let’s see what you’ve got.

Not getting enough Holy crap! in your life? Then try this on for size:

Holy crap!

Oh yes, you definitely want to click on that to embiggen the heck out of it. This teeny 610 pixel wide version does nothing to give you the sense of awe and glory in this spectacular picture. The full size image is a whopping 7227 x 3847 pixels! Warning: you’ll lose an hour of your life gaping at it.

That, duh, is Saturn, taken by the ever-amazing Cassini spacecraft. It’s actually 75 different exposures stitched together, and was taken on August 12, just a little over a day after Saturnian equinox, when the Sun shines straight along the rings. The illumination from the Sun is about the same everywhere, but on the left the rings are illuminated by Saturn-shine glowing down on them, making them a bit brighter.

This picture keeps on giving, too. You can spot several moons if you look in the embiggenatisized version (most obvious is Janus on the left; all of the moons have had their brightness enhanced to make them more easily visible in this image). You can also see the subtle swirls and whorls of storms in Saturn’s upper atmosphere. And what’s that dark line on Saturn’s equator? That’s the shadow of the rings themselves, narrowed to a thin line due to the Sun angle.

Holy crap.

And yet, there’s more. Check. This. Out.

[Update; Oops: I got this image mixed up with another. I've struck through the old mistake, but leave it up as evidence that I blew it here. It happens sometimes. Sorry about the confusion, and my thanks to Joe Mason
CICLOPS Media Relations Coordinator, for pointing out my error.]

This is an old image (taken by Cassini in 2005) that shows a long streak, which I’ve highlighted with red arrows. New images taken in the past month at Saturnian equinox confirm that this streak is actually an expanding cloud of debris from the impact of a small meteoroid, probably about a meter across and moving at several dozen kilometers/second. It came in almost exactly parallel to the rings, leaving a path of wreckage and destruction many thousands of kilometers long.

This image, also taken at equinox, shows an elongated streak, marked by the red arrows. That streak, it’s been determined, is actually from the impact of a small meteoroid, probably about a meter across and moving at several dozen kilometers/second. It came in almost exactly parallel to the rings, As the debris cloud expanded, different orbital motions sheared it, leaving a path of wreckage and destruction 5000 kilometers long. [Update II: My thanks to Carolyn Porco for pointing out this explanation to me in the comments.]

Can I hear one final holy crap?

The image here was enhanced to bring out the streak. It turns out old images had similar streaks, but at the time they weren’t sure what they were.

It’s been thought for a long time that the rings were constantly bombarded by interplanetary interlopers, and now we have pretty good proof. This also makes me think this picture of Saturn’s rings from August really does show some object slamming into them at speeds dozens of times faster than a rifle bullet.

Cassini has been orbiting Saturn since 2004, and these images show the true power of being able to go to a place and stay there, taking picture after picture for many years. Every picture has a use, and old images can be reinterpreted when new data come in.

And we keep learning! Saturn is a forbidding, remote, fascinating, and enchantingly beautiful world, with secrets and surprises to keep us guessing and fascinated for decades. I’m very glad Cassini is there bring us these delights.

One of the most beautiful sights in the sky (at least, so I’ve heard, since I’ve never ^%$#&*# seen one) is an aurora. The Earth has a magnetic field that traps charged particles from the Sun, and due to complicated processes that are still being investigated these particles can slam into our air, causing it to glow (exactly) like a neon sign.

But we’re not the only planet with a magnetic field. And some moons have them, too. Check this image out:

That’s the north pole of Jupiter as seen by Hubble Advanced Camera for Surveys back in 2007 (the vertical black line is part of the detector that blocks the view). It’s an ultraviolet image, since the atmosphere glows brightest in the UV. The big oval is the main aurora, but see the dot with the curved tail to the right? That is due to Jupiter’s mighty magnetic field interacting with the moon Io, a volcanic and violent satellite about the same size as our own Moon. The interaction is truly terrifying: over a million amps of current flows between Jupiter and Io as the magnetic field of the giant planet sweeps past the moon. To give you an idea of how much electricity that is, a typical car battery might crank at about 100-500 amps, so imagine 10,000 cars all lined up, powered only by the current flowing between the planet and its moon…

Io doesn’t have a magnetic field on its own, but the sulfur ions spewed out by Io’s volcanoes get swept up by Jupiter’s magnetic field, linking the two objects. So Io is connected to Jupiter magnetically, and a vast current flows from the moon down to Jupiter’s poles. Where the current hits, the atmosphere glows, and you see that bright dot. As Jupiter spins, that footprint marches across the planet, fading with time, leaving the curved tail of emission.

Ganymede is another moon of Jupiter, and as befits the massive planet, Ganymede is the largest moon in the solar system, bigger than Mercury! It too interacts with Jupiter’s magnetic field, and it too leaves a footprint on the jovian atmosphere. That can be seen on the left of the picture above. Ganymede has a strong enough magnetic field on its own that it has what amounts to a protective bubble around it, much like the Earth’s magnetic field protects it from the Sun’s solar wind. As far as we know, Ganymede is the only moon to have such a bubble.

And now, for the first time, astronomers have been able to measure the size of Ganymede’s auroral footprint and see that it fits the expected size from what’s known of Ganymede’s magnetic field. They’ve also seen that it varies in strength over 3 different time intervals: 100 seconds, 10-40 minutes, and 5 hours. This means there are variables, changes in the magnetic fields of the two bodies, which is modulating the amplitude of the interaction. Most likely the longest is tied to Jupiter’s rotation, which is over 9 hours. The other two may be due to local changes in the plasma environment of Ganymede, and to the way its magnetic field connects with Jupiter’s.

So what does all this mean? Well for one, it means Jupiter’s raw might and power scare the crap out of me. I’m glad it stays 600 million kilometers away! Second, it means that the Jupiter system is incredibly complex and well worth studying, to understand how magnetic fields in space interact and produce the kind of environment we see. A manned mission to Jupiter is unlikely any time in the next century, but the more we understand about such things, the more we can apply them to places we can go, like Earth orbit, and possibly Mars too.

Knowledge gleaned from scientific observations is never abstract; there are always applications for it. That’s because everything really is connected to everything else… whether it’s a physical connection blasting countless electrons into an alien atmosphere, or a connection we ourselves make by applying what we know to what we want to know. That’s science.

[Update to my note; the blog software upgrade is tomorrow, Wednesday, not today. Sorry for the confusion, BABloggees! The Hive Overmind is doing a blog upgrade today from about 9 a.m. to 2 p.m. Eastern time, and during that period commenting will be turned off. Don't panic!]

Scientists using data from the Cassini spacecraft have found something amazing: a lightning storm on Saturn that’s lasted for nearly eight months! And it’s still going.

Long lasting storms on planets aren’t unusual; the Great Red Spot on Jupiter is at least 400 years old! But active lightning storms are more difficult to detect… unless you happen to be close by. Giant lightning bolts create vast discharges of radio energy, and Cassini’s has an instrument sensitive to them. It’s been monitoring Saturn for about five years now, and has seen lots of lightning storms. The previous record holder was 7.5 months, for a system that lasted from November 2007 to July of last year.

This new one has been raging since February, and shows no signs of abating. Storms on Saturn are a bit more violent than on Earth: they can be 3000 km (1800 miles) across, and discharge energy at rates 10,000 times higher than storms here on Earth!

Yikes.

Cassini image of a lightning storm from July 2008. Credit: NASA/JPL/Space Science Institute

Sure, this stuff is cool — giant killer electrical storms , woohoo! — but it’s also science. As these waves of energy plow through Saturn’s ionosphere, scientists can use them to map out the structure of Saturn’s environment and learn how the giant planet behaves. That’s really the whole point, of course.

That, plus planet-spanning disaster-movie sized lightning storms! Cooooool.

After a long and nervous wait for those of us stuck on Earth, the world’s most famous observatory is back on the job! Behold!

Click to embiggen. Credit: NASA, ESA, and the Hubble SM4 ERO Team

W00t!

That’s NGC 6217, a spiral galaxy as seen by Hubble’s Advanced Camera for Surveys, a workhorse detector on Hubble that went on the fritz in January 2007. But when the STS-125 brought the Space Shuttle Atlantis to Hubble, it also carried two new cameras and the tools to fix two older, busted ones, including ACS. After a daring series of repairs and upgrades, Hubble is now back up to speed.

This ACS image is gorgeous. NGC 6217 is relatively close by, at a distance of roughly 80 million light years (note that some early press said it was 6 million light years away, which is incorrect). The gas and stars in the middle form an exquisite rectangular bar across the core due to complicated gravitational interactions, and you can easily pick out huge numbers of glowing pink star forming areas, where stars are being born in prodigious quantities. And even from this vast distance — 800 quintillion kilometers (500 quintillion miles) — Hubble can still pick out individual stars in the spiral arms. These are the biggest, baddest, and brightest ones, the stars that will someday explode as monstrous supernovae… and you can rest assured astronomers will be using Hubble or its successors to observe them when they do.

But there’s more! Check out this deep image of the cluster Omega Centauri:

Wow! This picture is from the newly installed Wide Field Camera 3, the third generation such camera on Hubble. The image shows a portion of the globular cluster Omega Centauri, a giant ball of millions of stars that orbits the Milky Way. This image alone shows about 100,000 stars at all stages of evolution, from slowly glowing yellow to furiously churning red — stars at the ends of their lives, about to fizzle out into tiny, hot white dwarfs — and finally sapphire blue stars, helium-rich objects also nearing cosmic senescence.

But of all the gorgeous images released today, there is one that is very, very special to me:

It may not look like much to you, but to me that picture sings. As far as the science goes, it’s a spectrum (the light from an object sliced up into thousands of individual colors) of the titanic star Eta Carinae, a monster 100 times the mass of the Sun — the upper limit for how big a star can be without tearing itself apart — that will some day soon explode as a supernova, and may even be a gamma-ray burst. This image shows the light from the star dissected, displaying the velocity and chemical composition of the massive gas clouds surrounding the star: huge lobes of material ejected in a violent outburst from the star over a hundred years ago. Spectra like this let us keep tabs on Eta Car, monitoring it for changes that will gives us clues on how this bizarre and frankly scary star is behaving.

But to me, as important as the science and knowledge gained from this data are, it’s the mere fact of its existence that is so important.

A prelaunch STIS in 1997.

The image is from the Space Telescope Imaging Spectroscope, a camera I worked on for more than six years. I helped calibrate and test STIS as it was built, and I watched as it roared into space aboard Discovery in 1997. For three more years I worked on the incredible data from STIS, displayed on my computer screen, as this camera tool the pulse of the Universe with spectra and images of objects as close as asteroids in our solar system to galaxies 10 billion light years away. I worked on data that laid out to me the chemical composition, temperature, and distance of stars, galaxies, gas clouds, gamma-ray bursts, and so much more. I sweated blood on STIS, and so when it suffered a debilitating short in 2004 I was pretty upset. It was like losing a member of the family.

STIS sat silent for five years, orbiting the Earth in Hubble’s instrument bay. But in May 2009, astronauts were able to repair the shorted computer board on STIS during a very dramatic space walk. After that I heard nothing for months, which was making me nuts.

But no longer. I’m not at all ashamed to say that when I saw this STIS graphic of Eta Car, I choked up, and there were — oh hell, there still are as I write this — tears in my eyes. I’m so proud of the team that built STIS, the hundreds of people who used it, the incredible people at NASA, and the men and women of our astronaut corps who risked their lives to make sure our eye on the sky is clear, clean, updated, and razor-focused.

With its quiver full of new and newly repaired cameras, as well as shiny new gyroscopes and other critical pieces of equipment, we’ll be seeing more and better-than-ever scientific images and spectra from Hubble for many, many more years to come.

A few weeks ago my brother-in-law took this picture:

Click to embeegen (ha!). Actually, I helped take this shot; I held the flash while he took the pictures. We were bent way over into the lavender, and the buzz of dozens of bees was quite loud and more than a little menacing.

He’s a good photographer, and one of these days we’ll set up all my meteorites to get a nice gallery of them.