How many planets are in our galaxy?
Billions and billions of them at least. That’s the conclusion of a new study by astronomers at the California Institute of Technology, which provides yet more evidence that planetary systems are the cosmic norm.
The team made their estimate while analyzing planets orbiting a star called Kepler-32 — planets that are representative, they say, of the vast majority of planets in our galaxy and thus serve as a perfect case study for understanding how most of these worlds form.
“There are at least 100 billion planets in the galaxy, just our galaxy,” says John Johnson, assistant professor of planetary astronomy at Caltech and coauthor of the study, which was recently accepted for publication in the Astrophysical Journal. “That’s mind-boggling.”
“It’s a staggering number, if you think about it,” adds Jonathan Swift, a postdoctoral student at Caltech and lead author of the paper. “Basically, there’s one of these planets per star.”