Two exoplanets, a rocky like Earth and other gaseous like Neptune, evolve to a very small distance from each other, a discovery that intrigues astronomers who had never observed a similar phenomenon.
It is like imagining that instead of a full moon rising on the horizon, lifted a giant gas planet appears to be three times bigger than this, say the researchers, whose work was published Thursday in the U.S., in the online edition of the journal Science.
That world is so different to ours does exist and is located about 1,200 light years from Earth (one light year corresponds to 9,460,000 kilometers). This star system was named Kepler-36, in honor of a U.S. space telescope dedicated to searching for planets outside our solar system (exoplanets).
"These two planets pass very close to each other," said Josh Carter, the Center for Astrophysics, Harvard-Smithsonian, and one of the principal authors of these investigations.
"These (planets) are the closest we have ever been observed in a planetary system," added astronomer Eric Agol, University of Washington.
The two planets are at their closest point every 97 days on average and are separated by a distance five times lower than that between the Earth and Moon, which translates into about 1.9 million kilometers.
These astronomers found two planets by analyzing the data collected by the Kepler telescope capable of detecting an exoplanet as it passes in front of a star then briefly lowering its splendor.
This new planetary system has only two planets in orbit around a star that could resemble our Sun, but several thousand years older.
The planet closest to the star, Kepler-36b, is rocky like Earth, about 1.5 times larger than this, and has a mass 4.5 times higher. This planet orbits its star in 14 days at an average distance of less than 17.7 million kilometers.
The second planet, Kepler-36c is a gas and 3.7 times larger than Earth and a mass eight times.
This "hot Neptune", the largest of the two, named for its proximity to its star, orbiting around it in 16 days at a distance of 36.21 million miles.
With reference to Kepler-36c is much larger than our moon, its movement must offer a spectacular view of the sky seen from Kepler-36b. Situation highly unlikely to experience any population, since all indications are that there is no life on these planets.
Such proximity between two exoplanets also causes enormous gravitational forces that compress and expand, these astronomers suggest, trying to understand how these two very different planets in orbits could be found so close.
In our solar system, rocky planets like Earth, Mars and Mercury are close to the sun, while those that are gaseous like Jupiter, Saturn, Uranus and Neptune evolve at a greater distance.
However, although the Kepler-36 star system was the first to demonstrate a closeness between a rock and a gaseous planet, it is likely that this phenomenon is not an unusual circumstance outside our galaxy, the Milky Way.