Astronomers have known about the existence of planets around other stars since the early 1990s. Since then, over 500 confirmed extra-solar planets (or “exoplanets”) have been discovered. Most of them are gas giants like Jupiter, since these are the easiest to detect. The holy grail, as it were, of exoplanet searches is Earth-like planets in habitable zones around other stars. The habitable zone is the orbital distance from a star that would permit the presence of liquid water and Earth-like life. The Kepler mission, launched into space in 2009, has found more than 1,200 candidates for Earth-sized planets around other stars, with over 50 of these possibly in the habitable zone.
The trick is to confirm these candidates, as they could turn out to be mundane companion stars. The confirmation process takes a long time — out of the 1,200+ candidates detected by Kepler, only 15 have been confirmed so far. But help is on the way. A new instrument, called High-Accuracy Radial velocity Planet Searcher (HARPS-North) has been designed to aid in the confirmation of Earth-like exoplanets detected by Kepler. HARPS-North will see first light in the spring of 2012 on the 3.6-meter Telescopio Nazionale Galileo in the Canary Islands.
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“Per aspera ad astra”!