lONDON: Scientists have found the most similar planet to Earth so far discovered, which is only a little bigger and seems to be made of very similar materials.
Describing the results in Nature, two independent teams of scientists found the planet has a diameter of 9,200 miles (around 1.2 times that of Earth), and contains a rocky interior and an iron core. That’s where similarities to our home planet end, as Kepler-78b zips around its star every eight and a half hours at a distance of 1m miles, and the surface temperature on this planet is probably at least 2,000C higher than the hottest day on Earth.
The scientists used the transit method to determine the orbit and size of the planet Kepler-78b – where they watched the light given off by the parent star, Kepler-78, and noted how often and how much the light dims every time the planet passed in front of it.
Calculating the planet’s mass involved watching the motion of the star itself and watching how the tiny gravitational pull of the planet made the star wobble.
The total mass of Kepler-78b, which is 400 light years from Earth, was calculated as around 1.7 times that of Earth and its density is around 5.3g per cubic centimetre (slightly lower than Earth’s 5.5g per cubic centimetre).
“This is a very important result, and goes to the question of how common planets like our own are in the galaxy,” said Bill Chaplin, an astrophysicist at the University of Birmingham. “Getting a good estimate of the size of the planet and a good estimate of the mass – is still very rare.”
Subhanjoy Mohanty, an astrophysicist at Imperial College London, said the discovery was an important step towards finding true analogues of Earth. The Guardian