1. Where We Are….
As of November 21, 2016, over 3400 confirmed exoplanets had been found, with over 4500 additional candidate exoplanets. We can look at these planets in a number of different ways, but here, I choose to look at them by plotting the mass of the planet (in Jupiter masses) against the duration of that planet’s year (orbital period, in days). Not all of the confirmed exoplanets are shown in this plot, but there are a number of interesting things we can see from this plot. The two big observations are that (1) there aren’t many planets like those in our own solar system. That’s actually a result of the way that our detection methods work – the two best methods so far, the transit method and radial velocity searches, are most sensitive to large planets, and to planets that have short orbital periods. As our methods improve, and as new capabilities become available, we fully expect to see the Solar System-like part of this plot fill in. The other observation is (2) there are a lot of planets out there that are nothing like anything in our own solar system! To me, this is an exciting discovery, because from that, we suddenly understand that the diversity of worlds is far greater than we would have expected from our system’s planets.
Red = transits
Black = Transit timing
Blue = radial velocity
Green = Pulsar timing
Yellow = microlensing
Orange = Eclipse timing
Purple = direct imaging
Light Blue = Orbital Brightness Variations