1. Exoplanets are everywhere
When I was an astronomy graduate student in the early 1990s, no one knew if there were any other planets in the Universe other than the eight that orbit our Sun. Since scientists believe the formation of life requires a planetary surface or ocean, the question of planets orbiting other stars loomed large. Then, in 1995, we discovered our first extrasolar planet, or exoplanet. It was a true scientific revolution. Fast-forward to 2024 and we’ve discovered so many exoplanets that astronomers can say with confidence that just about every star you see at night hosts a family of worlds.
After examining their growing census of worlds, astronomers made an exciting discovery. Count up five of the stars you see in the night sky and one of them will have an exoplanet in what’s called the ‘habitable zone’. This is the band of orbits around a star where liquid water can exist on a planet’s surface. Because water is so useful in biochemistry, it’s considered a prerequisite for life. Today, astronomers know that planets are everywhere and, better yet,
