Goldilocks Globe—Part 1

The search is on for planets around nearby stars. In only the last decade or so have astronomers begun to find so-called extra-solar planets around other stars. Prior to that, they felt pretty confident that planets must be out there, but the difficulties of verifying their presence were beyond the tools at hand. More powerful telescopes and more powerful computers are now allowing these discoveries to be made.

How do astronomers detect planets circling other stars? There is as yet no telescope capable of adequately zeroing in on a planet in another solar system—a star is just too bright and the planets too small and dim to see them. But if the planets are there, they will exert the tiniest gravitational pull on their star, causing it to wobble a minute amount, as they circle. Today’s big telescopes, backed up by super computers, have the sensitivity to discern this miniscule quavering of a star and even infer what kinds of planets are causing the tremble. In fact, the planetary motion laws that Newton gave us can be used to determine how many planets are there, their masses, and the size of their orbits. It’s amazing what the laws of physics will allow us to discover indirectly!

So the search for extra-solar planets has kicked into high gear in the last several years. Different teams of astronomers using different facilities feed off of and compete with each other and keep the enthusiastic juices flowing. New telescopes and techniques are coming on line all the time and are racking up impressive findings.

Until a few years ago astronomers strongly suspected, but had no direct evidence of, planets beyond our solar system. The discoveries are now piling up quickly—on the order of 400 hundred planets or more have been found to date. (I give a rough number, because the tally mounts almost daily.) Last year NASA sent up the Kepler Space Telescope—especially designed to ferret out extra-solar planets. The Kepler team has already announced locating several more worlds out there. A formal NASA report is imminently due, that will likely add dramatically to the total.

So what has been found so far? The vast majority of recently discovered planets are huge—the size of Jupiter and more. The tools available thus far are not yet sensitive enough to find smaller worlds, like Earth, but Kepler will undoubtedly change that. Super Jupiters are nice to find, but they hold little chance of harboring life of a type anything like us—their gravity is too great, their atmosphere is too thick, and their temperatures are usually too high.

On to the Goldilocks planet next time…