They didn't use a space telescope, or a huge ground-based scope like the Keck or the Gemini, or even the sort of backyard telescope some planet-hunters rely on to gather evidence of alien worlds. Instead, a team of European and American astronomers started with a clever new analytical technique, applied it to a set of existing observations archived by the European Southern Observatory, and made what could be the biggest planet discovery since — well, since the announcement of a world in the nearby Alpha Centauri star system three weeks ago.
The fact that big planetary discoveries are occurring so close together is a measure of how fast the exoplanet field has exploded in recent years. And the announcement a few weeks back was an exciting one indeed. That new planet orbits a star close to Earth, and it's Earthlike in size as well. Its surface is probably molten lava – which pretty much rules it out as a candidate for life — and that's where the even newer planet wins out. Known as HD 40307g, it circles its home star once every 320 days or so, at a distance that puts it right in the star's Goldilocks zone, where temperatures are not too cold or too hot, but just right for water-based life like ours — if it happens to be there.