Have we found an alien Earth?

A team of astronomers based at the European Southern Observatory have announced the discovery of more than 50 new exoplanets orbiting nearby stars.  This is the largest number of such new worlds ever announced at one time.  One of these planets may enjoy conditions favorable for life on its surface.

Image of HD 85512 b

This artist’s impression shows the planet orbiting the Sun-like star HD 85512. (Image credit: ESO/M. Kornmesser)

The planets were found using the HARPS instrument on the 3.6m telescope at ESO’s La Silla Observatory. The HARPS (High Accuracy Radial velocity Planet Searcher) instrument is a very high resolution spectrometer used to measure the motions of a star with extraordinary precision. A planet in orbit around a star causes the star to regularly move towards and away from observers on Earth. Due to the Doppler effect, this back and forward movement causes a shift of the star’s spectrum towards longer wavelengths (called a redshift) as it moves away and towards shorter wavelengths( blueshift) as it approaches. This tiny shift of the star’s spectrum can be measured with HARPS and used to infer the presence of a planet.

Loading player…

One newly discovered planet, HD 85512 b, is best hope found so far for a habitable exoplanet. HD 8512 b is thought to be only 3.6 times the mass of the Earth and is located at the edge of its star’s “Goldilocks zone”, the narrow zone around a star where water may be present as a liquid on a planet’s surface if the conditions are right. The planet orbits the star HD 85512 which is 36 light years away in the southern hemisphere constellation of Vela (the Sail). HD 85512 is a K class star, older and somewhat hotter and brighter than the Sun. This planet is one of sixteen super-Earths (very large terrestrial- as opposed to gas giant- planets) discovered by HARPS.

The HARPS team so far have found that about 40% of stars similar to own Sun have at least one planet smaller than Saturn (which is 95 times more massive than Earth). The majority of exoplanets of Neptune mass (about 17 times the size of Earth) or less seem to be in systems with multiple planets. Planets seem to be common out there and abodes for possible life seem to be not particularly rare. So where is everybody?