A team of astronomers announces that they have identified an asteroid orbiting the sun faster than any of its known relatives. Measuring only one kilometer in diameter, it was spotted from Chile about ten days ago.
The rock, known as 2021 PH27, orbits our star every 113 Earth days . It is the shortest orbital period of any known asteroid in the Solar System. Considering all objects (asteroids, comets, planets and moons), only Mercury does better, completing an orbit in 88 days. 2021 PH27 follows a very elliptical trajectory, sometimes approaching our star within twenty million kilometers of the Sun's surface. At such a distance, the surface of the asteroid becomes hot enough to melt lead (about 500 degrees Celsius).
The object was first spotted on August 13 using the powerful 570-megapixel Dark Energy Camera (DECam) of the Cerro Tololo Inter-American Observatory (Chile) . The researchers were then able to determine its orbit over the following days through further observations from the DEC, supported by tracking operations conducted from the Las Campanas observatories in Chile and South Africa.
Getting this close to the Sun also has other consequences. The object experiences the strongest gravitational effects of any known object in the Solar System. These are manifested by a slight oscillation of the elliptical orbit of 2021 PH27, which in fact will probably collide with the Sun, Mercury or Venus in several million years, the researchers found.
Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington and leader of the discovery team, estimates that 2021 PH27 is about a kilometer wide. The object may have originated in the main asteroid belt, between Mars and Jupiter, before being thrown inward by gravitational interactions with one or more planets.
According to another hypothesis, it could also be a cometary remnant once born in the very outer regions of our system, as evidenced by the marked inclination of the orbital trajectory (32 degrees) from the plane of the Solar System. Further observations could help solve this mystery riddle. For that, we will have to wait a bit. Right now, the asteroid is indeed moving behind the Sun from our perspective. It won't reappear until early next year.
