NASA Confirms Closest Rocky Exoplanet to Earth
NASA's Spitzer Space telescope just confirmed that a newly discovered exoplanet is indeed the closest rocky planet to orbit a star other than the Sun, just 21 light years away. It goes by the name HD219134b, and orbits a star that can be seen with the naked eye, located in the Cassiopeia constellation.
The planet was originally discovered by the HARPS-North instrument on the Italian Galileo National Telescope. In addition to being the closest rocky exoplanet, it's also the closest exoplanet which can be seen transiting, or crossing in front of, its star. As a result, it is easier to detect than most exoplanets and can be studied in much more depth.
"Transiting exoplanets are worth their weight in gold because they can be extensively characterized," said NASA JPL project scientist Michael Werner in a statement. "This exoplanet will be one of the most studied for decades to come."
HD219314b is also in a unique spot in relation to Earth, allowing telescopes to actually see it transit its star. This could help scientists determine if it has an atmosphere and the composition of said atmosphere. As the planet transits its star, astronomers can glean chemical information from the dimming starlight.
A rocky composition is one of the foremost criteria astrobiologists look for when gauging habitability, but sadly, this particular planet is way too close to its parent star to support life. Its year is a not-so-lengthy 3 days long, and it has a mass approximately 4.5 times that of Earth (though it's only 1.6 times the size). The planet was found using the radial velocity method, which measures the amount of gravitational "tug" that a planet exerts on its parent star.
"Most of the known planets are hundreds of light-years away," said co-author Lars A. Buchhave of the Harvard-Smithsonian Center for Astrophysics. "This one is practically a next-door neighbor."