Following the finding of seven habitable exoplanets in TRAPPIST-1, astrophysicists found the harmony of arrangement in the planetary system. This harmony makes the planets become stable.

NASA announced last February to have found seven habitable exoplanets in TRAPPIST-1, about 40 light years away from Earth. The planets are discovered by the NASA's Spitzer Space Telescope.

Three of the seven exoplanets in TRAPPIST-1 are expected to have a habitable zone. However, scientists were puzzled that the arrangement of the exoplanets in TRAPPIST-1 is so tight. So the gravitational shake would make the planets to collide each other.

However, that will not happen, according to astrophysicist Daniel Tamayo, from the University of Toronto Scarborough. At first, Tamayo found, in his computer model, that the seven exoplanets in TRAPPIST-1 would either collide with each other or fly apart to the outer space. However, he later found that the TRAPPIST-1 and its planets have a very special harmony in the planetary arrangement.

Such unique arrangement is able to keep the exoplanets in TRAPPIST-1 to be in balance and prevent them from interfering with each other as they orbit the TRAPPIST-1 for billions of years. Tamayo and his three colleagues, Hanno Rein, Cristobal Petrovich and Norman Murray published their findings in The Astrophysical Journal Letters Volume 840, Number 2.

All the exoplanets in TRAPPIST-1 are so close to their main star, making their orbit is very short. Some planets have only 1.5 days to finish its orbit to TRAPPIST-1 as the main star, while the maximum time is 19 days. The orbit of the planets around the star has a similar resonance to our solar system.

One of the exoplanets in TRAPPIST-1, the second planet, completes five orbits in almost exactly the time the first planet makes its eight. This balance of orbit is similar to those of Pluto and Neptune resonance, as Pluto finishes its two orbits when Neptune finishes its third one. Watch the news about the finding of exoplanets in TRAPPIST-1 from NASA Jet Propulsion Laboratory below: