(CNN) — A newly discovered asteroid is approaching our sun, much closer than planet Earth itself.
The asteroid, named 2021 PH27, completes an orbit around the Sun every 113 days and approaches 20 million kilometers from our star.
This gives this space rock the distinction of having the shortest known orbital period for an asteroid and just the second shortest orbit around the sun after Mercury, which takes 88 days to complete its orbital journey around our star.
Scott Sheppard, an astronomer at the Carnegie Institution for Science, discovered the asteroid in twilight observations made by Brown University astronomers Ian Dell’Antonio and Shenming Fu on August 13. Dell’Antonio, a physics professor, and Fu, a doctoral student, took the images using the Dark Energy Camera mounted on the 4-meter Víctor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile.
Various aspects of the asteroid surprised Sheppard.
The asteroid is 1 kilometer long and “it is likely that there are very few asteroids of this size in the inner solar system that we are not aware of,” he said.
“2021 PH27 gets so close to the Sun that its surface can reach temperatures of 482 ° C, hot enough to melt lead,” Sheppard said by email. “Due to these extreme temperatures, it is unlikely that 2021 will be composed of any volatile material, and most likely it will be made up of rock with perhaps some metal like iron.”
It has an unstable orbit that crosses the orbits of Mercury and Venus on its way around the sun. In a few million years, the asteroid’s orbit will likely cause its doom. The rocky fragment could collide with Mercury or Venus, or with the sun itself, or be ejected from its current position in the solar system.
The asteroid is so close to the sun’s massive gravitational field that it experiences effects on its orbit, Sheppard said.
The newly discovered asteroid is just one of about 20 Atira asteroids, which are those that are completely within the Earth’s solar orbit.
Although there are a few known asteroids that get as close to the sun as 2021 PH27, their orbits are much longer.
“Some of these asteroids have been seen to have dust in their orbits, suggesting that the asteroids are slowly fragmenting or cracking due to the extreme thermal stresses these objects experience,” Sheppard explained.
A notable example of this is Phaethon, the asteroid that behaves like a comet which creates the Geminid meteor showers that occur in our skies every December.
Tracking an asteroid
But where did this space rock come from? That’s one of the questions Sheppard wants to investigate next, but he has some ideas based on preliminary observations.
The asteroid has likely detached itself from the main asteroid belt between Mars and Jupiter, but Sheppard has not ruled out the possibility that 2021 PH27 is actually an extinct comet.
“It could be an extinct comet, since comets are known to come from the outer Solar System in elongated, long-period orbits and interact gravitationally with the inner planets to achieve more circular and shorter-period orbits that keep them in the System Solar indoors for long periods of time, “Sheppard explained. The inner planets are Mercury, Venus, Earth, and Mars.
When this happens, some of the elements of the comet evaporate until it stops looking like a comet and only the remnants remain.
Sheppard often searches for incredibly distant objects in the solar system and beyond. However, it is also crucial to understanding the population of asteroids near Earth’s orbit. Near-Earth asteroids have the possibility of impacting with it in the future, but some of them are incredibly difficult to observe because they approach our planet during the day.
“Space within Earth’s orbit has been relatively unexplored to date,” Sheppard said. “It is difficult to see the region towards the Sun because of its extreme brightness.”
But the Dark Energy Chamber has a large field of view, making it a powerful tool for searching for objects that would otherwise go unnoticed, like 2021 PH27, especially during the twilight hours, when the Sun goes down and just right. before leaving.
Following Sheppard’s discovery, astronomer David Tholen of the University of Hawaii measured the asteroid’s position and predicted where it might be observed the following night. This allowed several telescopes to observe the asteroid from Chile and South Africa on August 14 and 15. These astronomers postponed the observations for their own research in order to help learn more about the asteroid.
“Although the time of telescopes is precious, the international nature and love of the unknown make astronomers very willing to put off their own science and observations to pursue exciting new discoveries like this one,” Sheppard said. “We are very grateful to all of our collaborators who have allowed us to act quickly on this discovery.”
Soon the asteroid will pass behind the sun and will not be observable until early 2022. Sheppard is eager to learn more about the asteroid’s composition and origin.
“Where do these inner asteroids come from? Some are recently detached Main Belt asteroids, others could be extinct comets, but there could be another population of origin, such as the Vulcanoids, which are a hypothetical population of asteroids,” Sheppard said.