Discovering new asteroids roaming the solar system is not exceptional, we have millions of these small stellar bodies orbiting the sun and we have been cataloging them for decades. But 2021 PH27, the asteroid recently discovered at the Carnegie Institution for Science, has several quirks that make it almost unique.
This rock of about 1 km in diameter takes only 113 days to go around the sun, at a distance of 20 million from the star. That makes it the shortest known orbit asteroid in our solar system, and the second if we take into account the 88-day orbit of the planet Mercury.
The discovery has been made by Scott Shepard, who comments in 9News that “you rarely see asteroids of this size” with orbits so close to the Sun. It only crosses the orbits of Mercury and Venus, the Earth is already something far away by 2021 PH27.
Shepard has two theories for the origin of this asteroid. Either it is a comet whose tail has completely evaporated or it is a former tenant of the asteroid belt that was deflected by the gravitational pull of the inner planets of the solar system. Regardless of one or the other, the professor estimates a temperature of 900º C for when 2021 PH27 is closer to the Sun. And as this temperature is capable of melting lead, it is suspected that the asteroid is made up of rocks and metals that are more resistant to high temperatures.
2021 PH27 does not have a very promising future. It is expected that at some point during the next 20 million years (a “little while” in the great time scale of the universe), planetary gravity and the heat of the Sun will fragment the asteroid little by little until it ends up completely disintegrating it. And that’s if it doesn’t end up colliding with Mercury or Venus, of course.
As long as that does not happen, 2021 PH27 becomes part of a short and exclusive list of the so-called Atira asteroids, made up of those bodies whose orbits are within the Earth’s orbital path. It is an area that is relatively close to us, which due to the brightness of the Sun we have not explored much compared to the rest of the sky.