This story got my attention a while ago, but for some reason I forgot about it until recently. It is astounding to think that it was only in 1995 that we discovered the first extra-solar planet (exoplanet), and less than 20 years later the tally is at over 1000!
The first few hundred exoplanets were discovered using the Doppler technique, where an orbiting planet causes its parent star to move back and forth in a rhythmic and regular manner which can be detected by shifts in the star’s spectral lines. However, in 2009 NASA launched its Kepler Space Telescope, and this led to more and more exoplanets being detected using the transit technique, and as of now most have been discovered by Kepler using this technique. You can read more about these two techniques in one my previous blogs here.
There is also a great episode of BBC Radio 4’s “In Our Time” which was broadcast last year (2013) which discusses exoplanets. The link is here, it is still available to listen to. Enjoy!