There are more planets than stars

I have long wanted to put forth the point that there are more planets than stars in the Universe. This goes to my contention that it is reasonable, even necessary, to believe that there is copious life in the Cosmos. After all, from the time when Earth’s surface cooled to when life began to appear was relatively short. It appears that all it takes for self-replicating molecules to get going is the right conditions. With so many planets, the opportunities are so vast, it has surely happened over and over again.

But I couldn’t make this exact point. I still made the same effective point, but I had to rely on the trillions and trillions of stars. Of course, plenty of people have inferred over the years, especially the past decade, that there must therefore by billions, maybe trillions of planets. But we need something more concrete. We need observation. And now it looks like we’re there:

Three studies released Wednesday, in the journal Nature and at the American Astronomical Society’s conference in Austin, Texas, demonstrate an extrasolar real estate boom. One study shows that in our Milky Way, most stars have planets. And since there are a lot of stars in our galaxy — about 100 billion — that means a lot of planets.

It could be that the Milky Way is a weird outlier, a place where planets are easy to make. But there isn’t any reason to suspect that. The observations show that we are an average galaxy with an expected array of stars. What’s more, we are seeing what happens around stars. It isn’t just that these giant gas balls form in space and that’s that. No, it’s much more. Most of them come with their own planetary pals. An accurate average of the star-to-planet ratio remains to be seen (they say 1.6 planets per star, but that is probably extremely low), but it is clear that we’re talking about trillions and trillions out there.

None of this changes the thrust of my argument about exo-life, but it does allow me to be much more specific. This is very nerdexciting.

How many planets are in our galaxy?

The answer is 50 billion. But I find the number in the Goldilocks zone far more interesting.

At least 500 million of those planets are in the not-too-hot, not-too-cold zone where life could exist. The numbers were extrapolated from the early results of NASA’s planet-hunting Kepler telescope.

Hey look, every Facebook user could have one Goldilocks planet all his or her own.

These numbers could change drastically, but don’t expect to ever see any minuscule estimate by any measure. We have billions of stars in the Milky Way alone; we can predict the number of planets should reasonably be in the billions just by that fact. And if we venture our minds outside our little corner of the Universe, we realize there are more stars than grains of sand on Earth. The total number of planets in the Universe is undoubtedly in the trillions. And I’m probably being conservative. Earth is likely to be mind-blowingly mundane.