Jupiter Has An Identical Twin, 17,000 Light-Years Away

Astronomers have discovered a planet that is nearly identical to Jupiter, circling a star 17,000 light-years away from the Earth. In terms of mass, the exoplanet, dubbed K2-2016-BLG-0005Lb, is nearly the same as Jupiter. While K2-2016-BLG-0005Lb has a mass of 1.1 times that of Jupiter, the star that it orbits has a mass of about 60 per cent of the Sun.

The near-identical twin is also around the same distance from its star as Jupiter is from the Sun. K2-2016-BLG-0005Lb is 420 million miles away from its star, while Jupiter is 462 million miles away.

The planet and its star are located in the constellation Sagittarius. An international team of astrophysicists discovered the exoplanet using data from NASA's Kepler satellite telescope collected in 2016. In the Milky Way galaxy, the telescope has discovered over 2,700 verified planets so far, but this system is twice as far away as any ever discovered by Kepler.

The astrophysicists used Albert Einstein's Theory of Relativity and a technique known as gravitational microlensing to discover the system. The study has been submitted to the journal Monthly Notices of the Royal Astronomical Society and is available as a preprint on ArXiv.org.

David Specht, a PhD student at The University of Manchester, is the study's lead author. To locate an exoplanet utilising the microlensing method, the researchers looked through Kepler's data from April to July 2016, when the spacecraft was regularly monitoring millions of stars around the Galaxy's centre. The goal was to find evidence of an exoplanet and its host star bending and amplifying the light from a background star as it passed through the line of sight.

Dr Eamonn Kerins, the principal investigator for the Science and Technology Facilities Council grant that funded the work, said in a statement that to see the effect at all, the foreground planetary system must be nearly perfectly aligned with a background star. The odds of a planet affecting a background star in this way are in tens to hundreds of millions to one against. However, at the centre of our Galaxy, there are hundreds of millions of stars. So, for three months, Kepler just watched them, added Dr Kerins.

At the same time as Kepler, five other ground-based surveys also looked at the same area of the sky. However, Kepler, which orbits the Earth at a distance of roughly 135 million kilometres, saw the anomaly slightly earlier and for a longer period of time than the other teams watching from Earth.

“Kepler was never designed to find planets using microlensing so, in many ways, it's amazing that it has done so,” adds Dr Kerins