Look, I’ve been around the block a few times. I’ve spent my whole life as an astronomer, so I’ve seen pretty much every big, bright object there is in the sky.

However, "pretty much" != "all". It’s still possible to surprise me, and folks, let me tell you: the Gemini telescope’s observation of the nebula Kronberger 61 did just that!

Wow! [Click to ennebulenate.] It looks like a buckeyball or a soccerball; my wife pointed out it looks like the shape you get when you use a bubble maker to make a bunch of bubbles all stuck together. Kn 61, as it’s called, is actually a planetary nebula, the gas flung off by a star like the Sun as it dies. You can get the details (along with many pretty pix) of how this works in a recent post of mine. In a nutshell, when a star runs out of useable hydrogen fuel in its core, it expands into a red giant and expels a huge wind of gas. This strips away the outer layers of the star, revealing the hot, dense core. Ultraviolet light from that star then lights up the surrounding gas, making these gorgeous nebulae.

The exact mechanisms for this process, however, are still not clear. (more…)

When I was younger, it was pretty common on clear nights to see me at the end of my driveway with my telescope. And one of my favorite targets to observe was (and still are) globular clusters: hundreds of thousands, and sometimes millions of stars all bound together in a tight ball due to their gravity. And one of the best of those is the fabulous M15… and when it’s seen by Hubble, well, it’s simply spectacular:

Holy wow! Click to englobulenate – I had to shrink the image a lot to get it to fit here, so as gorgeous as this is it’s a shadow of the higher-res version… or the ginormous full-res one!

M15 is relatively nearby as globulars go, about 35,000 light years. Over 150 of these objects orbit our galaxy, and so some are quite far away. Not only is it close, but M15 is also fairly densely-populated, its stars orbiting each other like bees around a beehive, making it a pretty easy target for amateur astronomers. It was one of the first things I’d go after once it got dark in the autumn, and it would appear as a fuzzy ball in my 25 cm ‘scope. Of course, when you aim the 2.4 meter mirror of Hubble at it, well. You can see for yourself.

This false-color image is a combination of two pictures; one taken in visible light (colored blue; in reality the filter used let through yellow and red light), and the other in near-infrared (colored red). That selects out redder stars; the brightest ones are red giants, stars nearing the ends of their lives, and the fainter ones are lower-mass stars that are still busily fusing hydrogen into helium in their cores.

If you look to the left and a bit below the cluster’s center, though, a blue glow sticks out among all the red. If you do grab the seriously super high-res version of the image, you get a much better look at it. I’ve zoomed in on it here. It’s clearly not a star; the blue halo is much larger than any star image, and you can see the rim on the left hand side is bright. What gives?
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One of my favorite types of objects in space are the thin, ethereal shells of gas stars create when they die. So I was thrilled^* to see this new image of one taken in exquisite detail by the Hubble Space Telescope:

[Click to supernovenate.]

I studied weird soap bubbles like this for quite some time for both my post-graduate degrees, and they still fascinate me. This one, called SNR 0509, is actually a very interesting example. There are lots of ring-shaped objects in the sky — the Helix nebula (seen below) may be the most canonical — but usually the ring itself is thick, the width of the band being a large fraction of the object diameter itself. Why does SNR 0509 have such a thin ring?
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So I’m sitting at home catching up on email, and I get a note from my friend Whitney who does press and outreach for the NASA infrared observatories Spitzer and WISE. There’s a new image from WISE that might be of interest, she claims. OK, I think, clicking the link; WISE images are usually a bit odd — astronomical objects tend to look very different in the far infrared than what I’m used to –but even then, when the image came up on my browser, I was struck by a major dose of holy frakitis:

Wow. And holy frak!^* What the heck is that thing?

You might be forgiven if your first thought is that it’s the space station from "2001: A Space Odyssey". But in fact it’s something a bit more distant: it’s NGC 1514, the gas and dust surrounding a dying star system about 700 light years away.

I am somewhat familiar with these objects, having studied one for my Master’s degree, and a similar object for my PhD. But planetary nebulae, as they’re called, are so diverse and weird that understanding one, or even several, doesn’t always help in understanding all of them. And this one is seriously freaky. Those rings, lovely as they are, turn out to be quite difficult to explain.

OK, here’s the very brief skinny: (more…)

Every year, this gets harder.

Not that deciding what pictures to use in 2006, 2007, or 2008 was all that easy! But astronomy is such a beautiful science. Of course it has scientific appeal: the biggest questions fall squarely into its lap. Where did this all begin? How will it end? How did we get here? People used to look to the stars asking those questions, and coincidentally, for the most part, that’s where the answers lie. And we’ll be asking them for a long time to come.

But astronomy is so visually appealing as well! Colorful stars, wispy, ethereal nebulae, galactic vistas sprawling out across our telescopes… it’s art no matter how you look at it. And our techniques for viewing the heavens gets better every year; our telescopes get bigger, our cameras more sensitive, and our robotic probes visit distant realms, getting close-up shots that remind us that these are not just planets and moons; they’re worlds.

So every year the flood of imagery takes longer to sort through, and far longer to choose from. And the choices were really tough! This year leans a bit more toward planetary images than usual, but that’s not surprising given how many spacecraft we have out there these days.

I don’t pick all these images for their sheer beauty; I consider what they mean, what we’ve learned from them, and their impact as well. But have no doubts that they are all magnificent examples of the intersection of art and science. At the bottom of each post is a link to the original source and to my original post on the topic, if there is one. If you disagree with my picks, or think I’ve missed something, put a link in the comments! All the pictures have descriptions, and are clickable to bring you to (in most cases) much higher resolution version. So embiggen away!

And welcome to my annual Top Ten Astronomy Pictures post. Enjoy.