NASA’s little satellite that could, Swift, recently celebrated its seventh year in space. It blasted into orbit on November 20, 2004, starting a mission that would increase our understanding of the most violent events in the universe, and shatter cosmic distance records.

I wrote about Swift six years ago, on the first anniversary of its launch, and the funny thing is not a whole lot has changed except for the numbers. It’s still going strong after 2500+ days in orbit, and instead of dozens of gamma-ray bursts seen after one year, now it’s seen well over 600. Gamma-ray bursts are the mind-numbingly violent explosions of stars that signal the births of black holes, and each event releases as much energy in a few seconds as the Sun will over its entire lifetime. Happily, the Earth is nowhere near any potential GRB candidates (the nearest is about 7500 light years away, far enough that any damage it could do to us would be relatively mild), but if one were, say, 100 light years away, it would cook us like a whelk in a supernova.

Observing GRBs is Swift’s primary mission, and it’s performed outstandingly. It’s spotted what might be the most distant cosmic explosions ever seen, at 13.14 billion light years away from Earth. It saw the brightest GRB ever detected. But it’s also surveyed the sky, looking at high-energy light from sources near and far. It’s mapped our nearby galactic neighbors the Andromeda (shown above) and Triangulum galaxies in ultraviolet. It’s even observed near-Earth asteroids.

You can see the latest GRBs seen by Swift online, and there’s also a fun little iPhone/iPad app you can download that shows you Swift info, including the latest GRB detected and where Swift is in its orbit over the Earth.

I worked on Education and Public Outreach for Swift for many years, and it’s really nice to see it still pumping out fascinating and important science. Happy birthday to Swift and congratulations to the Swift team!

Image credits: NASA; Image credit: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP)

The eyes of many astronomers — and the eyes of their telescopes — were aimed at the asteroid 2005 YU55 a few days ago, when it passed the Earth at the relatively close distance of about 320,000 km. One of those eyes was actually in space as well: NASA’s Swift satellite. This spacecraft was designed to look at the sky in the ultraviolet, X-ray, and gamma rays, all high-energy forms of light emitted by the most violent events in the universe: exploding stars and gamma-ray bursts.

But the Sun emits UV, and rock can reflect this light, too. So Swift observed YU55 as it passed us, and got this very interesting footage of it, what I think is the coolest I’ve seen so far:

[You can also watch it on YouTube if you prefer.]

Pretty neat, and by looking at the rock at different wavelengths, we can learn about its structure and composition, too.

But I know what you’re thinking: in the video, why did YU55 curve around as it moved? As it turns out, I was expecting this when I watched the video! What’s going on^*?

The asteroid is in elliptical orbit around the Sun, but over the short period of time covered by this video — about 20 minutes — it’s essentially moving in a straight line. The reason the path is all bendy is because Swift itself is in motion! Swift orbits the Earth, circling us once every 90 minutes or so. As it moves around us, its viewpoint is changing, and that motion is reflected in the asteroid.
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In late March of 2011, an extraordinary event occurred: a black hole in a distant galaxy tore apart and ate a whole star (I wrote about this twice at the time; here’s the original post, and a followup article including a Hubble image of the event).

Now, there’s more info: the black hole, lying at the center of a galaxy nearly 4 billion light years away, has about 8 million times the mass of the Sun. When it tore the star apart, about half the mass of the star swirled around the black hole, forming twin beams of matter and energy that blasted outward at a large fraction of the speed of light. The folks at NASA’s Goddard Space Flight Center made a great animation to show this:

The star was ripped apart by tides. The thing about black holes is, they’re small: this one was probably about 15 million kilometers across. A typical star is about a million km across (the Sun is 1.4 million kilometers in diameter, for comparison). This means the star could get really close to the black hole, and that’s why it was doomed. The force of gravity drops with distance, so as the star approached, the side of it facing the black hole felt a far greater force than the size facing away. That stretched the star, and the stretching increased as the star got closer. At some point, the force was so great it exceeded the star’s own gravity, and it could no longer hold on to its material. The black hole won — as they usually do.

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In honor of Star Wars Day (May the Fourth be with you)…

I’ve been running around a lot the past week, and a few stories I wanted to write about slipped past me. One in particular was about an asteroid collision in the main belt between Mars and Jupiter; it was observed by the orbiting telescopes Swift and Hubble. All the more aggravating, I spent years working with both observatories (research with Hubble, and educational outreach with Swift)! I really wanted to write about this. Plus, asteroid collisions are cool, and y’all should get a chance to hear about them.

Happily for me, the folks at NASA (specifically Scott Wiessinger who makes videos for the space agency) put together a good story about the collision in easy-to-digest video form:

Awesome. Now back to my regularly scheduled running around.

I recently wrote about a mind-boggling event: astronomers capturing what are apparently the final moments in a star’s life as it was literally torn apart by a black hole.

Today, NASA has released some new pictures of the event, including this Hubble Space Telescope shot:

[Click to embiggen.]

I know, it may not look like much at first. But remember what you’re seeing: the violent death of a star ripped apart by the gravity of a black hole… and it’s happening 3.8 billion light years away! That’s about 40,000,000,000,000,000,000,000 kilometers, so the fact that we can see it at all is pretty amazing. And terrifying.

In this false-color Hubble image, the galaxy and explosion are marked. Pretty much everything you see in the picture is a distant galaxy, a billion of more light years away. Normally, the host galaxy itself would appear as a dot, at best with some small amount of fuzz around it, the glow of billions of stars reduced by the incredible distance. But the dying light of the star increased the galaxy’s brightness by a lot. A whole lot.

This image (click to greatly embiggen!) is a combination of visible light (white), ultraviolet (purple), and X-rays (yellow and red) from NASA’s Swift observatory, the satellite that first detected the explosion. While the spikes are not real — they’re just an optical effect from the telescope itself — it still speaks to the drama of what we’re seeing.

And so just what are we seeing?
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On March 28, 2011, NASA’s Swift satellite caught a flash of high-energy X-rays pouring in from deep space. Swift is designed to do this, and since its launch in 2004 has seen hundreds of such things, usually caused by stars exploding at the ends of their lives.

But this time was hardly "usual". It didn’t see a star exploding as a supernova, it saw a star literally getting torn apart as it fell too close to a black hole!

The event was labeled GRB 110328A –a gamma-ray burst seen in 2011, third month (March) on the 28th day (in other words, last week). Normal gamma-ray bursts are when supermassive stars collapse (or ultra-dense neutron stars merge) to form a black hole. This releases a titanic amount of energy, which can be seen clear across the Universe.

And those last two characteristics are certainly true of GRB 110328A; it’s nearly four billion light years away^*, and the ferocity of its final moments is not to be underestimated: it peaked at a solid one trillion times the Sun’s brightness!

Yegads. I’m rather glad this happened so far away. That’s not the kind of thing I’d like to see up close.

Although initially cataloged as a GRB, followup observations indicated this was no usual event. The way the light grew and faded seemed to fit better with a star getting torn apart. And what can do that to an entire star? A black hole. So instead of the star in question forming a black hole, it apparently literally fell victim to one!

The observations indicate the black hole in question may have as much as half a million times the mass of the Sun, meaning it’s very probably a supermassive black hole in the very center of a distant galaxy. Hubble Space Telescope observations (not yet released to the public) also place the event very near the center of a galaxy, which is consistent with this scenario.

So what happened?
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