Today, astronomers announced that they have found a new exoplanet, a planet orbiting another star. Nearly 500 exoplanets have been found in the past 15 years, so what's the big deal, you may ask? The big deal is that this planet and star are from another galaxy!
[Artist's impression of the alien planet; click to extragalaticate.] There is a whole lot of coolness going on here, so strap in.
OK, first, this planet is in our own Milky Way galaxy. The star, called HIP 13044, is about 2000 light years away, well inside our galaxy. So how do we know it's from a different galaxy? All the stars in our galaxy orbit the galactic center, like planets orbit around a star. But many years ago, astronomers noticed that many stars in the sky have the same sort of motion as they orbit, as if they all belong to streams of ...
