It's the large end of the scale that's been a fascination of mine for some time. I remember as a teenager running into the classic 1977 video Powers of Ten, that starts hovering a meter above the hand of a sleeping man in a park, and then moves away from him at an increasing speed, moving ten times faster every ten seconds. Before much time has elapsed -- and the whole video is under ten minutes long -- we are outside of the known universe, and our own "Local Group" of galaxies is a mere dot in the center of the screen. Then we dive back down toward the sleeping man, this time covering ten times less distance every ten seconds, and finally are centered on a single proton in a carbon atom in one of his DNA molecules.
Since 1977, of course, we've learned a lot more about each end of the scale. We now know that the universe itself is anisotropic -- the stars and galaxies are not uniformly distributed across space, but exists in superclusters and filaments, with enormous empty spaces in between -- accurately if spookily called "cosmic voids." (One of them, the Boötes void, is nicknamed "The Great Nothing," and is so large that if the Sun was at the center of it, the night sky would be completely black, and we would not have had a telescope powerful enough to find out about the existence of other stars until the 1960s.)
The paper, entitled "Isotropy and Statistics of the Cosmic Microwave Background Radiation," is an analysis of data from the Planck spacecraft, which has taken measurements for years of the radiation spread across the cosmos that is the remnant of the first flash of light at the moment of the Big Bang. You'd expect that it would be fairly uniform -- given that the Big Bang kind of happened everywhere at once -- but the curious result of the research is that there is a "warm hemisphere" and a "cold hemisphere" of the universe, as measured by the deviation of the temperature from the average of only slightly above absolute zero -- and weirder still, that in the middle of the "warm hemisphere" is a giant cold spot.
[Image courtesy of the Planck Telescope Project]
So there's your moment of "geez, we are really tiny" for today. On the Planck map picture above, the entire Milky Way -- 53,000 light years across, composed of about 250 billion stars -- is a single minuscule dot. All of which makes our little struggles on this Pale Blue Dot seem rather inconsequential, doesn't it?
As will be obvious to any long-time readers of Skeptophilia, I have a positive fascination with things that are big and scary and can kill you.
It's why I tell my students, in complete seriousness, if I hadn't become a teacher I'd have been a tornado chaser. There's something awe-inspiring about the sheer magnitude of destruction they're capable of. Likewise earthquakes, hurricanes, wildfires...
But as sheer destructive power goes, there's nothing like the ones that are produced off-Earth. These are the subject of Phil Plait's brilliant, funny, and highly entertaining Death From the Skies. Plait is best known for his wonderful blog Bad Astronomy, which simultaneously skewers pseudoscience and teaches us about all sorts of fascinating stellar phenomena. Here, he gives us the scoop on all the dangerous ones -- supernovas, asteroid collisions, gamma-ray bursters, Wolf-Rayet stars, black holes, you name it. So if you have a morbid fascination with all the ways the universe is trying to kill you, presented in such a way that you'll be laughing as much as shivering, check out Plait's book.
[Note: If you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]