Every year, thousands of incredible images of the sky are taken from observatories on the ground and in space, from spacecraft, and from amateur astronomers. And it seems that the people who make these images are getting better with time, creating nothing short of art.

And every year picking my favorites for the Top Ten list gets ridiculously harder. I fret about this each time (just as I did for the Top Tens of 2009, 2008, 2007, the 2007 Runners up, and 2006). But I've never seen anything like 2010; I went through over 1000 pictures, and even when I was merciless it was hard to get it down to 30. The agony of picking 10 was too much.

So to heck with it. I chose 14. Why? Well, for one thing, it's my list. But I also want to find images that are not only beautiful, but also tell a scientific story... as well as one that finds that spot in your brain that simply pops with wonder and awe.

This year, I found so many with that quality to them! So why limit myself? Some of the ones I chose may at first seem simple, or inelegant, but I picked them because they're more than just a pretty shot. They're telling us something wonderful and fundamental about the Universe. Astronomy is one of the handful of sciences which can appeal to both our eyes and our brains... as you'll see here. 10 14 times over.

Use the slider bar at the top to browse the images and get a brief description underneath, and click the big images themselves to go to a more thorough article. But whatever you do, make sure you click through to the higher-resolution versions of these images, because it's only there you'll get the full, incredible view they deserve.

Globular clusters are hundreds of thousands of stars packed into a tightly jammed ball, each orbiting the cluster center like a bee circling a hive.

NGC 6934 is one such globular, a single example of more than 150 that orbit our Milky Way Galaxy. It's 50,000 light years, such a great distance that its magnificence is greatly reduced, making it not much more than a fuzzy blob through most telescopes... unless you happen to have the Hubble Space Telescope at your command. Then this bustling city of stars becomes a dazzling jewel.

This image is false color; what you see as blue is actually taken through a red filter, and what looks red is actually infrared. Astronomers sometimes do this with two-filter images, to help our eyes separate out the colors.

In this case, it shows that most of the stars in the cluster are probably lower mass than the Sun, still fusing hydrogen into helium in their cores, but a few have aged to the point of becoming red giants, swelling up and cooling off. Such is the fate of our Sun in a few billion years... and studying distant globular clusters like NGC 6394 helps us understand how how our nearest star will someday die. I picked this image because it's a relatively unheard-of but beautiful cluster... and I love the way the stars look like jewels.

Get the high-res version here.

Image credit: ESA, Hubble, NASA

The Cassini spacecraft has been orbiting Saturn since 2004, and has been featured frequently both on my blog and in these Top Ten lists. Its views of the ringed planet and moons has been nothing short of spectacular time and again.

This shot reminds me why. The moons of Saturn orbit it almost all on the same plane, so Cassini sometimes sees them near each other in the sky. And if things play out just right, they even pass directly in front of each other.

That's exactly what happened here: icy Rhea, Saturn's second largest moon, is seen here superposed on the giant moon Titan. Despite catastrophic appearances, they were in no danger of collision: Titan was over a million kilometers from Rhea when Cassini snapped this shot. Note that Rhea is covered in craters big and small, while Titan's thick atmosphere blocks us from seeing its surface directly. Do you also see the ring of material apparently floating above Titan? That's a haze layer composed of hydrocarbons like methane, ethane, and even benzene. Titan's atmosphere is twice as thick as Earth's!

Note also that Titan is three times larger than Rhea and is in fact comfortably bigger than the planet Mercury; it's truly one of the most aptly-named worlds in the solar system.

Get the high-res version here.

Image credit: NASA/JPL/Space Science Institute

The Lunar Reconnaissance Orbiter has been circling the Moon since June 2008, taking incredibly high-resolution images of our neareast astronomical neighbor. It's photographed craters, ancient lava beds, mountains, and cliffs, but this image really stands out to me: it shows a house-sized boulder which rolled down a hill and landed inside a crater like a golf ball at a Putt-Putt course!

The left side of the picture is a hill which goes downhill to the right. The landscape flattens out in the middle, and you can see bits of rubble and debris from landslides at the point where they meet. A billion years ago or more, something must have dislodged that gigantic rock, setting it rolling down the hill. Not being round, it bounced along in the Moon's 1/6th gravity, leaving ruts dug into the powdery surface. It slowed when it hit the flatter surface, and almost came to a stop just past that 60-meter (200 foot) crater. But it must have teetered backwards (see how that last rut goes past the rock?) and then slid down into the crater itself, where it finally came to a stop.

It's easy to think that the Moon is mostly dead and unchanging, but when you look more closely - really, really closely - you'll see evidence of a dynamic world, with subtle beauty and fascinating structures. And we've only explored a tiny fraction of it. What else is there to see in the remaining 36 million square kilometers?

Get the higher-res version here.

Image credit: NASA/GSFC/Arizona State University

Whenever a new type of instrument is used to examine the skies, surprises are guaranteed. And when the Wide-Field Infrared Survey Explorer (WISE) started scanning the heavens in 2010, it returned one amazing view after another. My favorite by far is this one, showing NGC 1514, a dying star shedding material.

This image, in the far-infrared, is very different than optical shots of the nebula, which show it looking more like a disk. It's not certain just why this object has these two rings, but it's likely that dust ejected from the dying star is slamming into gas previously thrown off. That older gas is most likely in an hourglass shape, common in such objects. Perhaps the dust is hitting the inside of that hourglass figure, making the rings. Maybe it's a different reason entirely. We don't know!

And that makes me happy. Mysteries are fun, and new telescopes are bound to add to them, while solving others. WISE was designed to do a survey, which means it looked at anything and everything in the sky. A lot of what it found will have to be followed up with bigger telescopes. But until we get another powerful far-infrared telescopes, some of these weird objects will just have to wait to reveal their secrets.

Get the higher-res version here.

Image credit: NASA/JPL-Caltech/UCLA

This isn't a microscopic photograph of a bacterial culture! It's actually of rolling, hummocky dunes near the north pole of Mars. Taken with the Mars Reconnaissance Orbiter's powerful HIRISE camera, the normally grey basaltic sand of the dunes is covered with pinkish dust literally made of rust - iron oxide.

What makes this image so bizarre, though, are the dark, parallel tendril-like features scattered throughout. What the heck are those? One clue is that they always seem to stretch downhill, as if something is flowing. Another can be found in the tendrils located left of center and down a bit: there's a fuzzy pink oval emanating from one of them. Under magnification, you can see it's a dust cloud... the debris raised up after an avalanche of sand on the Martian surface!

Those tendrils are from the darker material under the pink sand. When dry ice under the surface warms up in the summer, it disturbs and dislodges the gray basaltic sand around it. This slides downhill, creating these weird, hair-like features. It's no surprise that some people mistook them for some form of life on the Red Planet! But I don't see the need to make up fantasy-based scenarios for pictures like this one, when we can see that Mars is fantastic enough.

Get the higher-res version here.

Image credit: NASA/JPL/University of Arizona

The Sun is a common target for astronomers both professional and amateur. It's so big and bright that you can really see a lot of detail, and every year a lot of pictures of it hit the 'net. You can get jaded from them all.

Which is why Alan Friedman's solar portrait blew me away when I saw it. It's actually a composite of two pictures: the outer limb of the Sun combined with a seperate shot of the Sun's disk. Not only that, he inverted the shot of the disk, essentially taking the negative. It gives the Sun a fuzzy, eerie appearance, and startled me when I saw it. I've never seen the Sun displayed in quite this way, giving it a beauty and delicacy I wouldn't thought possible. It's truly the most amazing picture of the Sun I've seen this year. And don't miss Alan's close-up shots of the limb, either!

Get the higher-res version here.

Image credit: Alan Friedman, used with permission.

I've been doing this a long time, and I've seen it all: galaxies and planets, gas clouds and moons, stars being born and stars dying... but when I saw this picture, I knew there were yet surprises in the sky.

When I saw this I literally gasped out loud; I had never seen any structure in space like it. And when I read what it was, my amazement did not decrease: it's the dusty wind of a dying star.

The object, called AFGL 3068, is a binary star, two stars in an 800-year orbit around one another. One of them is a red giant, a star near the end of its life. It's blowing off massive amounts of dark dust, which is enveloping the pair and hiding them from view. But the system's spin is spraying the material out like a water sprinkler head, causing this giant and delicate spiral pattern on the sky. And by giant, I mean giant: the entire structure is about 3 trillion kilometers (about 2 trillion miles) across.

Get the higher-res version here.

Image credit: ESA/NASA & R. Sahai

For over two centuries asteroids were just points of light in telescopes (hence the term asteroid, which means "starlike"). Until recently, that is: we're a spacefaring race now, and we can send our robots to sniff out these giant rocks up close... and in July, the European Space Agency probe Rosetta flew past the asteroid Lutetia, returning amazing close-ups of the rock.

This picture, which I borrowed from my friend Emily Lakdawalla at the Planetary Society Blog (I fiddled with the contrast and brightness a bit to bring out the darker side) was taken at closest approach. Lutetia is about 130 km (80 miles) across, and is the largest asteroid we've visited. You can see it's a lumpy, battered, rock, pitted with craters. The details are stunning: giant boulders held by the weak gravity dot the surface, parallel grooves mark stress fractures in the surface (or secondary deposits of material ejected from impacts?), and shadows highlight the contours.

We're just beginning to understand the nature of asteroids - and given that every now and again one of them pays Earth a catastrophic visit (just ask the dinosaurs) - it's good idea that we learn as much about them as we can.

Get the higher-res version here.

Image credit: ESA 2010 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA & Emily Lakdawalla

Speaking of asteroid collisions, in January 2010 the automated skywatching telescope LINEAR spotted what looked like a comet orbiting the Sun in the inner asteroid belt, just beyond the orbit of Mars. It looked decidedly odd, so Hubble was pointed at it... and what it saw was so bizarre it caused a big stir in the astronomical community: the aftermath of a violent collision between two asteroids in space!

The picture is unprecendented: an X-shaped streak of light with a dramatic 50,000-kilometer-long tail sweeping away. Apparently, an asteroid roughly 150 meters or so across - which you can see as a point of light at the upper left tip of the X - was hit at high speed by a smaller rock only a few meters across. The smaller object was vaporized by the energy of collision, which would've had the same yield as an atomic explosion!

The tail is from sand-grain to pebble-sized debris from the explosion moving away due to pressure of sunlight, which acts like a very gentle wind on the particles. The other line of the X is probably from a piece of rubble ejected off the main rock, leaving its own trail of debris behind. Judging from changes in the debris shape over time, the collision probably happened in February or March 2009, but the asteroid was up during the day at that time and was unobservable. It took several months to discover it, and a few more to understand what this strange object was telling us.

Collisions like this are estimated to happen roughly once per year in the asteroid belt, but the distance makes them very hard to observe. Hopefully, as more survey telescopes come online, we'll see more of these spectacular events.

Get the higher-res version here.

Image credit: NASA, ESA, and D. Jewitt (UCLA)

One glance at this picture lets you know why M51 is commonly called The Whirlpool. At 23 million light years away, it's visible through binoculars (barely; I always have a hard time spotting it), so when you point something like Hubble at it you know you'll be getting an incredible view.

This gorgeous shot is actually a composite of four different filtered images by Robert Gendler, an accomplished astrophotographer. The original release, done in 2005, was of course beautiful, but Robert took a stab at it and was able to make it even better.

The Whirlpool is actually two galaxies interacting with one another. The spiral galaxy is nearly face-on, and you can easily trace the magnificent arms, laced with red gas clouds forming new stars, and dark lanes of dust created when stars are born and when they die. The other galaxy is the orange blobby one, a dwarf irregular. It may have already passed through the bigger galaxy twice, and will eventually merge with it. We think all big galaxies grow by consuming smaller ones in this manner. In a few hundred million more years there won't be two galaxies left to see, just one somewhat bigger one. Our own Milky Way Galaxy probably underwent a similar event many times!

Get the high-res version here.

Image Credit: NASA, Hubble Heritage Team, (STScI/AURA), ESA, S. Beckwith (STScI). Additional Processing: Robert Gendler

There are two pictures this year that made my list that aren't strictly astronomy, but I couldn't resist. The first is this one, the aurora australis - the southern counterpart to the northern lights - as seen from above by astronauts on the International Space Station.

Charged particles from the Sun stream along the Earth's magnetic field, guided to the north and south poles, where they crash into our atmosphere and generate light. The color of the light depends on the molecule or atom hit; in this case, the green glow is due to oxygen.

Although the particles generating the light tend to be 80 - 160 km up (50 - 100 miles), the space station is even higher. This view is also well off to the side; the astronaut who took the picture was looking at the limb of the Earth, several thousand miles away. All in all the color, perspective, and the amazing glowing stream combine to make this a lovely and decidedly unearthly photograph from space.

Get the higher-res version here.

Image credit: NASA/Expedition 23

Space near the Sun is mostly empty, devoid of gas and stars. But travel 7500 light years in the direction of the constellation Carina and you'll slam into one of the largest and most complex star-forming regions in the galaxy: the sprawling Carina nebula. Massive stars being born there blast out radiation and winds that sculpt the surrounding material, creating weird and wonderful shapes.

So what better way for astronomers to celebrate the Hubble Space Telescope's 20th year in orbit than to use it to take a huge mosaic of Carina? This astonishing portrait shows the towering pillars of gas and dust being eaten away by cosmic erosion; the narrow, focused jets of material blasting away from stars eating away at their cocoons; ribbons and sheets of compressed gas lighting up space; and the nascent stars themselves as they turn on for the first time.

Get the higher-res version here.

Image credit: NASA, ESA, M. Livio and the Hubble 20th Anniversary Team (STScI)

This is the second of the two not-strictly astronomy pictures in this list, and is also taken from the International Space Station. It shows the Space Shuttle Orbiter Endeavour just minutes before docking with ISS. Both the ISS and Endeavour were orbiting the Earth at 8 km/sec (5 miles/sec), passing into the dark side of the Earth, essentially experiencing sunset - which they do 18 times a day!

This image is beautiful, of course, showing the layered colors of sunset as seen from 350km (210 miles) above the Earth's surface. But this picture is also a metaphor for the Shuttle itself: this was the second-to-last mission of the Endeavour, and in fact the last misson for the Orbiter will be the last mission for the entire fleet: after that flight, the Space Shuttle program will be finished, the Orbiters retired, and an as-yet unnamed rocket system will take over. In the meantime, American astronauts will hitch rides on Russian rockets, as well as on the Falcon 9 rocket from the private company SpaceX, which recently had a wonderfully successful test flight.

As for the Shuttle... the last launch of Endeavour is scheduled for April 2011, when it really will fly into the sunset for the last time.

Get the higher-res version here.

Image credit: NASA

Choosing these images every year is tough, but this year there was one shot so outstanding that as soon as I saw it, I knew it would be Number One!

This jaw-dropping picture - an insanely huge mosaic of 32 pictures taken by astrophotographer and amateur astronomer Rogelio Andreo - is Orion... the whole constellation! [Here is a higher-res version - 4000 x 2600 pixels! - hosted on Flickr, or you can get it from his site itself.] If you look carefully you'll spot the familiar stars: orange Betelgeuse in the upper left, blue-white Rigel on the lower right, and his famous three belt stars in the middle.

If you have trouble seeing the pattern of stars, it's not surprising.  Rogelio used filters that show stars, but which also accentuate the vast amount of hydrogen gas in this part of the galaxy. The glowing nebulosity almost outshines the stars themselves!

How about a short tour? There's a lot to see:

At the top of the picture is the Lambda Orionis nebula, the huge red cloud straddling Orion's shoulders. The blue star roughly centered in it is Lambda Orionis itself, a massive, hot, young star that is so brilliant it's ionizing the entire nebula... which is dozens of light years across.

Lower down, a vast red ring of gas starts just above Orion's belt and swings down to just above his knees. That's Barnard's Loop, a spherical bubble of gas formed as one massive star after another exploded deep in the heart of Orion, each sending out octillions of tons of gas at speeds of thousands of kilometers per second! This material screamed outwards, slamming into and sweeping up the ambient gas in the region. This eventually snowplowed all that material into the bubble, which is heated today and glowing due to the still-thriving massive stars inside it. The Loop is about 300 light years in diameter - 3 quadrillion kilometers (2 quadrillion miles)!

In the center of the loop is perhaps the most famous gas cloud in the sky: the great Orion Nebula. It's 1500 light years away, yet easily visible to the naked eye; the Sun would be an invisible dot at that distance! But the nebula is churning out young stars which light up the gas, making this one of the brightest examples of stellar nurseries in our galaxy. If there are aliens in other galaxies looking our way, the Orion Nebula would be easily visible as a Milky Way landmark.

Above the great nebula and to the left a bit, hanging down from the leftmost star (Alnitak) is a straight line of gas, excited by the star. Superposed on that is a dense, dark globule of dust and molecules in the uncanny shape of a horse's head, as if the galaxy is playing a cosmic game of chess.

And finally, I must note the long, bluish nebulosity just to the right of Rigel at the bottom of the picture. When flipped upside-down, it becomes obvious why this is called the Witch Head Nebula! The resemblance to a witch is pretty amazing. Funny, too: when seen sideways it looks like a running ghost, and you'll see it sometimes called that as well. The perfect nebula for Halloween.

Any one of these pieces of Orion are shot so beautifully by Rogelio that they would deserve to be in this list, but all together... WOW. I mean, seriously. I've seen Orion a bazillion times; it's up in the south after sunset all winter long, and has so many wonderful objects in it that every amateur astronomer makes it a familiar destination for the telescope. I can't tell you how many times I've observed various nebulae in it, scanned it with binoculars, or just gazed at it with my own two eyes, soaking in its pattern and colors.

But I have never, ever, seen it like this. This picture has beauty, clarity, depth, sharpness, and most importantly sheer stunning breadth that makes it truly one of the most amazing astrophotographs I have ever seen. It's also a first: this is the first time I've picked an image by an amateur astronomer (as opposed to one from a professional observatory or spacecraft) for the number one slot. This photograph earned it.

Congratulations to Rogelio for this incredible work of art, my Number One pick for the best Astronomy Picture of 2010.

Get the stunning super-high-res version here.

Image credit: Rogelio Andreo, used by permission