2. Earth Is 18 Galactic Years Old
The solar system is zooming through interstellar space at around 500,000 miles an hour. Even at that rate, it takes about 250 million years to travel once around the Milky Way. The last time our 4.5-billion-year-old planet was in this same spot, continents fit together differently, dinosaurs were just emerging, mammals had yet to evolve, and the most profound mass extinction in the planet’s history—an event called the Great Dying—was in progress.
3. There’s a Monster Black Hole in the Galaxy’s Middle
Called Sagittarius A*, the supermassive black hole weighs in at more than four million times the mass of the sun. We’ve never seen this object directly—it’s hidden behind thick clouds of dust and gas. But astronomers have been able to follow the orbits of stars and gas clouds near the galactic center, which allowed them to infer the mass of the cosmic heavyweight hiding behind the curtain. It’s thought that supermassive black holes are parked in the cores of most galaxies, and some are feeding on nearby matter so greedily they shoot out jets of powerful radiation visible from millions of light-years away.
You can take a spin through the Milky Way’s chaotic center courtesy of a new animation released at the AAS meeting.