It's only the start of February, but already this year the Extrasolar Planets Encyclopedia has added six new planets.

There are pictures of fewer than two dozen planets orbiting stars outside the Solar System. But astronomers have discovered nearly nine hundred of them. Ever wonder how they find what they can't see? See Searching for Extrasolar Planets.

You can help in the search for extrasolar planets.

PlanetHunters

It's part of the Zooniverse citizen science project. You need to register to take part, but you can try out the tutorial and look through the guide, etc. without doing that. People are looking at data from the Kepler mission to search out patterns that suggest a planet is transiting (going in front of) a star.

Citizen scientists taking part in the PlanetHunters project found a planet in October 2012 from studying the data from NASA's Kepler mission. It’s been named PH1 and it orbits a double star which is also orbited by another pair of stars at about 900 times the Earth-Sun distance. PH1 is somewhat larger than Neptune and orbits every 137 days.

I'm a bit behind on new planets. The Planet Hunters project discovered a second confirmed planet last mongth - so there's now a PH2. It's in the habitable zone of its star, but is a gas planet like Jupiter so not likely to have life on it.

Planet Hunters have also found 31 good planet candidates, but there needs to be more data to confirm them.

If you want to join in the search, the website is Planet Hunters. I've been having a go, but I haven't seen anything that looks even vaguely promising. But you never know!