Far-off planet discovered in “habitable zone”

Astronomers announced on Monday the discovery of 50 new planets, including one so-called "super-Earth" that orbits at the edge of its star's "habitable zone." 

The discoveries were made with the High Accuracy Radial velocity Planet Searcher instrument, or HARPS, operated by the European Southern Observatory (ESO).

In a press release, the ESO said:

One of the recently announced newly discovered planets, HD 85512 b, is estimated to be only 3.6 times the mass of the Earth and is located at the edge of the habitable zone — a narrow zone around a star in which water may be present in liquid form if conditions are right.

According to The Washington Post, HD85512b "circles an orange star somewhat smaller and cooler than our sun about 36 light-years away." The planet circles its star every 59 days.

“If we are really, really lucky, this planet could be a habitat [like Earth]," Lisa Kaltenegger, of the Max Planck Institute for Astronomy, told the Post.

Astronomers have yet to determine if HD85512b is rocky like Earth or gassy like Jupiter. In addition to HD85512b, 15 other new planets announced on Monday have the right mass to be made of rock. But to determine if these planets have atmospheres, astronomers need to take pictures of them, something no telescope is powerful enough to do yet.

In its press release, the ESO described how these planets were found:

A planet in orbit around a star causes the star to regularly move towards and away from a distant observer on Earth. Due to the Doppler effect, this radial velocity change induces a shift of the star’s spectrum towards longer wavelengths as it moves away (called a redshift) and a blueshift (towards shorter wavelengths) as it approaches. This tiny shift of the star’s spectrum can be measured with a high-precision spectrograph such as HARPS and used to infer the presence of a planet.

"In the coming ten to twenty years we should have the first list of potentially habitable planets in the Sun's neighborhood," ESO team member Michel Mayor said in a statement. "Making such a list is essential before future experiments can search for possible spectroscopic signatures of life in the exoplanet atmospheres."