Astronomers have discovered the first ever interstellar comet.
Astronomers first discovered in the solar system an object that is most likely the first found interstellar comet. The comet, which received the designation C / 2017 U1 (PANSTARRS), moves along an unclosed hyperbolic orbit. This means that it flew from outside of our planetary system and will soon return to interstellar space. The announcement of the opening of a new comet is published on the website of the Center for Small Planets of the International Astronomical Union.
Most comets, like all bodies of the solar system, move in closed elliptical orbits. The period of their circulation around the Sun can be hundreds of years, but they sooner or later return. Hyperbolic or parabolic comets have a much higher speed and fly along non-closed trajectories - this means that they can visit the solar system only once, and then fly away forever into interstellar space.
Astronomers know several dozen parabolic and hyperbolic comets, but for the vast majority of them, the elements of the orbit are extremely inaccurately measured, so they can turn out to be "ordinary" comets with extremely elongated elliptical orbits.
But the comet C / 2017 U1 (PANSTARRS) is very different from them. According to the Center for Small Planets, the eccentricity of its orbit is about 1.2, that is, it has a knowingly hyperbolic trajectory.
"Further observations of this object are highly desirable ... This object may be the first indisputable case of the appearance of an interstellar comet," the report said.