An astronomer at the Carnegie Institution in Washington has just announced the discovery of 2021 PH27, an asteroid that orbits the Sun in just 113 days : it is the shortest known orbital period for an asteroid and the second shortest for any celestial body in our system. solar after Mercury, which takes only 88 days to complete one revolution. However, 2021 PH27 makes an elliptical orbit that makes it, in some sections, get much closer to the Sun: about 20 million km in the closest approach, compared to 47 million km for Mercury. The asteroid is about a kilometer in size and is in an unstable orbit that crosses those of Mercury and Venus, which means that it will probably be destroyed in a collision with one of these planets or against the Sun itself, or it will be ejected. from your current position.
2021 PH27 was discovered from images taken by a team of scientists from Brown University (United States) and obtained with the Dark Energy Camera mounted on the 4-meter Víctor M. Blanco Telescope of the Cerro Tololo Inter-American Observatory, in Chili. Studying these types of bodies is useful in helping scientists understand where asteroids originated and the forces that shaped the architecture of our solar system. “Most likely, 2021 PH27 has left the Main Asteroid Belt between Jupiter and Mars and that the gravity of the inner planets has shaped its orbit to its current configuration,” explains Scott S. Sheppard, the astronomer who made the discovery. .
“Although, based on its large 32 degree tilt angle, it is possible that 2021 PH27 is an extinct comet from the outer solar system venturing too close to one of the planets.” Because 2021 PH27 is so close to the The Sun’s massive gravitational field experiences general relativistic effects more strongly. This manifests itself in a slight angular deviation in its elliptical orbit over time, a motion called precession. The observation of Mercury’s precession puzzled scientists even that Einstein’s Theory of General Relativity explained its orbital adjustments over time. The precession of 2021 PH27 is even faster than that of Mercury. “2021 PH27 gets so close to the Sun that its surface temperature reaches around 482 degrees Celsius to the closest approximation, high enough to melt lead, “explains the scientist.
Identify possible impacts
Censuses of asteroids near and within the orbit of the Earth are crucial to identify those that could potentially impact our planet, but they are difficult to detect because they usually approach our planet during the day, while observations are usually made in the twilight. The new asteroid will shortly pass behind the Sun and won’t be observable from Earth until early next year, at which point observers will be able to refine its orbit with the precision necessary to give it an official name.
Text: Carnegie Institution of Washington
