This picture is so totally freaking cool I have half a mind not to explain, and just make you stare at it and boggle at just how freaking cool it is.
But of course I must explain it!
First off, what is it? Obviously, it's a giant blue hand reaching for a giant piece of cosmic smoked salmon! Dr. Manhattan must be hungry.
OK, duh, it's a nebula, a vast structure of gas several light years across and located about 17,000 light years away from Earth. Since this is a Chandra X-ray observatory image the gas must be terribly hot; only the most energetic events can give off X-rays. So what's heating the gas?
If you look at the wrist of the hand, you'll see a brighter swirl of gas. In the center of that blob is a tiny object, a neutron star called B1509: an incredibly dense sphere of subatomic particles, leftover when a massive star goes supernova. While the outer layers of the star explode outwards, the core of the star collapses, cramming twice the mass of the Sun into a ball only a few kilometers across. This newly born neutron star -- called that because the pressure is so great in the collapsed object that electrons and protons are rammed together to form neutrons -- is basically the definition of the word incredible: it spins several times per second, has a surface gravity millions of times that of the Earth (if you were on the surface you'd be crushed flatter than a good science fiction program's chances to be renewed on Fox), and has a magnetic field 30 trillion times that of the Earth's.
So how does that teeny tiny neutron star form this huge structure?
It's the magnetic field coupled with the rotation of the star. As it spins, the star sweeps up gas surrounding in its magnetic field. Through complicated processes that, to be honest, are not 100% understood, the star fires this swept-up material out in twin beams from its poles, a bit like a lighthouse, though a million gazilion times stronger.
The gas colored red in this false-color image is from a nebula named RCW 89, which is leftover gas from the original explosion of the supernova that formed the neutron star. It's close enough to the neutron star that when the beam of matter and energy slam into it, it heats up and glows. The beams are extremely high energy (colored blue in the image), and the gas in RCW 89 doesn't get quite so hot, so it emits lower-energy X-rays.
But look at the red nebula: see how there are lots of hot spots, arranged in a loop or a horseshoe? It turns out the neutron star isn't just spinning, it's also wobbling like a top does as it spins down. This process, called precession, makes the beams point in different directions over time, basically carving out a giant circle in the sky. That loop in the red gas is actually the historic record of where that beam hit the gas over the past millennium! In fact, astronomers could measure how hot those knots of gas are and determine their age, and find that they have been emitting X-rays for a little over 1000 years, consistent with the date of the explosion. In fact, as you go around the loop, each knot is slightly hotter then the next, which is just what you expect from a moving beam heating up the gas.
That also explains the fingers, too: each is a tower of gas heated by the beam as it made its giant sweeping circle in the sky. So not only do they look like fingers, they're also actually pointing to the knots of gas in RCW 89, the neutron star's way of saying "You're next."
The energies involved here are nothing short of mind-numbing. The clumps of gas in RCW 89 are so hot that they are storing the same amount of energy as the Sun gives off in 3 million years. If that really were a giant hand reaching for RCW 89, it better be prepared for a nasty burn.
And of course, the pareidolia aspect of all this is impossible to deny. It does look like a giant blue hand, and it really reminds me of the endoskeleton from a Terminator.
Or maybe I have my scifi shows wrong...