Kepler78b, an artistic rendering: “[The] planet has a similar size and density to
our world’s but circles its star in just 8.5 hours,” Elizabeth Gibney of Nature says.
Photo Credit: Nature/Marco Galliani; Media INAF
An article, by Elizabeth Gibney, in Nature News says that scientists have more information about a planet, Krepler-78b, that is similar to our in composition, but is much hotter than earth—with surface temperatures between 2,300 and 3,100 Kelvin (or between 2,026 and 2,826 Celsius). This planet could never be habitable, but it is noteworthy in that it gives us knowledge on how planets are formed and the similarities between them.
Two groups of researchers have for the first time succeeded in measuring the mass of an Earth-sized exoplanet — in this case, Kepler-78b, which is only slightly wider than Earth and orbits a star in the constellation Cygnus, 123 parsecs (400 light years) away. Astronomers are getting better at finding the many small, Earth-sized planets that scatter the Universe outside our Solar System, but finding clues to what they are made of is much harder.
The figures for Kepler-78b are published today in Nature1, 2 and show that the planet’s density is similar to that of Earth, suggesting that it also has a similar composition of rock and iron. That, however, is where the similarities end. Kepler-78b travels in orbit about 40 times closer to its star than Mercury is to the Sun; its year lasts just 8.5 hours; and its surface is thought to reach a scorching 2,300–3,100 Kelvin.
Kepler-78b is one of a recently-discovered class of exoplanets with orbital periods much shorter than one day, says astronomer Francesco Pepe of the University of Geneva in Switzerland, who led one of the teams that calculated the planet’s mass2. “It can be imagined like a lava planet rather than an Earth-like planet,” he says.The earth remains unique in that it is the only known planet that has the necessities to support human life. This makes perfect sense when you consider that humans evolved on, and adapted to, this planet, and not to another. The search for other planets that could support human life is similar in many ways to the curiosity of explorers from Europe who, hundreds of years ago, sought other lands and cultures. It is a desire to know what is out there and to determine how similar these places, these planets, are to ours.
It is unclear how Kepler-78b got so close to its star and whether it is falling in further, he adds.
You can read the rest of the article at [Nature News].