[I'm trying to catch up with all the news that's been released this week while I was off lecturing in Texas. This is Part 2 of a few articles just about exoplanets. Here's Part 1, and here's Part 2.]
A very interesting set of observations has resulted in a conclusion that is somehow, paradoxically, both expected and startling: there are hundreds of billions of planets in our galaxy alone! It's expected because all the research being done for the past few years has been zeroing in on how many stars have planets, and it's looking more and more like they're very common. I'll get into that in a sec. But it's also startling, because HOLY COW THERE MAY BE HUNDREDS OF BILLIONS OF PLANETS IN OUR GALAXY ALONE! Ahem. OK. So what's going on here?
The new result comes from what's called microlensing. The gravity of a star or planet ...
