What the Hell is That? (Number 2 in a series, if you want to guess, don’t read below the image.)
Yeast cells in a petri dish? Higgs Boson particles in the LHC? Nope, this fascinating image is an infrared view of the exact centre of our galaxy. The image is about one light year wide, and the animation loop covers a period of eight years. And it’s not obvious, but the moving stars are actually orbiting around the yellow cross at the centre of the image. In fact our sun is orbiting around that yellow cross, every orbit taking about 200 million years. That means the Sun is 22 1/2 in galactic years, just a young whippersnapper in it’s prime.
Cool new tunas so far, but it gets cooler. Again, it may not be obvious, but those stars are really moving. Look how slowly the other stars in the image are moving compared to the central stars. The only explanation so far is that they are orbiting something really massive at the yellow cross. In fact calculations show that whatever it is, it masses more than five million Suns! Well, astronomers have a pretty good idea what it is, they think it is a black hole, something that appears to reside at the centre of most if not all galaxies like our Milky Way.
Being a black hole, we can’t see it of course. It only reveals itself in x-rays and the motion of stars orbiting it. Is it eventually going to suck up the entire galaxy? No, more than the Sun is going to suck up the entire Solar System. Well, OK, yes, eventually everything in the Universe will get sucked into black holes. Black holes do slowly decay becasue they emit Hawking radiation, and eventually they will all be gone, there will be no more entropy possible, and the Universe will experience heat death, and be nothing but a near infinite incredibly thin cold near vacuum. That won’t be for about 10100 years though, so it’s safe to say that humanity has far more pressing concerns to worry about.
It’s still amazing to me what we know about our Universe now compare to when I was a kid. And I will continue to share images that amaze me. The black hole at the centre of our galaxy is now in the process of gobbling up a huge cloud of gas, if I can find a good picture of this I will post it.
(Image Credit: A. Eckart (U. Koeln) & R. Genzel (MPE-Garching), SHARP I, NTT, La Silla Obs., ESO It’s basically a NASA image and as such may be used pretty much freely for non-commercial purposes. “It is estimated that 3.71 X 10^10 “first-star-tonight” wishes have been wasted on Venus.” OK, a little astronomer humor there. With emphasis on little, I think it’s safe to say that not many stand up comics got their start in astronomy.)