NASA confirms discovery of nearest rocky exoplanet to Earth so far

The recently-announced Kepler planet that is receiving all the current attention is known as Kepler-452b, which orbits a star some 1,400 light-years away and which is located within the constellation of Cygnus, the swan-now almost overhead during the later evening hours.

HD 219134b is also the closest exoplanet to Earth to be detected transiting, or crossing in front of, its star and, therefore, flawless for extensive research.

“Transiting exoplanets are worth their weight in gold because they can be extensively characterized”, Michael Werner, project scientist for the Spitzer mission said in a statement. Much would depend, certainly, on the constituents of its atmosphere, assuming it has one, how much water is present, the surface topography, and so on – information that we have no way of gleaning at this time.

Scientists hope to learn even more about the new planet by studying it with NASA’s new James Webb Space Telescope. It can not be seen from Earth with the naked eye.

One possible appearance for the planet HD 219134b is seen in this artist’s image.

Radial velocity measurements allow researchers to determine a planet’s mass. Additional observations by NASA’s Spitzer Space Telescope confirmed that HD 219134b transits, or crosses the face of, its parent star from Earth’s perspective. “This one is practically a next-door neighbor”, said study co-author Lars A. Buchhave, an astronomer at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts.

The closest confirmed planet is GJ674b, just 14.8 light years away.

HARPS-North and its sister instrument HARPS in Chile look for planets by precisely measuring the colour of a star. This planet was determined to have a mass 4.5 times that of Earth, and a very quick three-day orbit around its star. NASA’s Spitzer Space Telescope confirmed the finding. Another is a Neptune-like world nine times more massive than Earth with a 47-day orbit; the third planet is 62 times more massive than Earth and takes 1,190 days to complete one lap around the host star. It is only 1.12 times the diameter of Earth, and although we don’t have an accurate value for its mass, it is quite likely a rocky world like Earth.

It has been hiding out in the M-shaped, northern hemisphere constellation Cassiopeia, “just” 21 light years from Earth.

Now that astronomers know HD 219134b transits its star, scientists will be scrambling to observe it from the ground and space.

This particular planet’s discovery is exciting because it’s part of the growing class of planets labelled super-Earths. “It can be considered a kind of Rosetta Stone for the study of super-Earths”, Michael Gillon, the lead scientist for the Spitzer detection, said in the announcement. That proximity to us makes HD 219134b a prime specimen. Planets like this, referred to as super-Earths, are ubiquitous throughout the galaxy, but we still don’t know a lot about them.

The ground-based telescope in Galileo National Telescope in the Canary Islands also found three more planets in the same star system.