The fastest asteroid in the solar system is discovered


A new asteroid revolves around the sun faster than any of its known relatives.

The space rock, known as 2021 PH27, circles our star every 113 Earth days, its discoverers determined. It is the shortest orbital period of all known objects in the solar system except the planet Mercury, which only takes 88 days to circle the sun.

However, 2021 PH27 moves on a much more elliptical trajectory than Mercury and therefore approaches considerably the sun – about 12.4 million miles (20 million kilometers) for the closest approach, compared to 29 million miles (47 million km) for the innermost planet of the solar system.

Related: The 7 strangest asteroids in the solar system

During these close solar passes, the surface of 2021 PH27 becomes hot enough to melt lead – around 900 degrees Fahrenheit (500 degrees Celsius), estimates the discovery team. Those deep dives in the sun’s gravity also mean the asteroid is experiencing the biggest general relativity effects of any known object in the solar system. Such effects are manifested by a slight oscillation of the elliptical orbit of 2021 PH27 around the sun, which the team observed.

By the way, this orbit is not stable in the long term. 2021 PH27 will likely collide with the sun, Mercury or Venus in a few million years, if it isn’t first ejected from its current path by gravitational interaction, team members said.

2021 PH27 was first spotted on August 13 by astronomers using the Dark Energy Camera (DEC), a powerful multi-purpose instrument mounted on the Víctor M. Blanco 4-meter telescope at the Inter-American Cerro Observatory. Tololo in Chile.

The team was able to determine the asteroid’s orbit over the next few days, thanks to further observations from the DEC and Magellan telescopes at the Las Campanas Observatory in Chile, as well as smaller telescopes in Chile and in South Africa operated by the Las Cumbres Observatory.

The PH27 push of 2021 postponed some sightings scheduled with these instruments, but the redesign was worth it, team members said.

“Although telescope time for astronomers is very precious, the international nature and love of the unknown make astronomers very willing to bypass their own science and observations to follow interesting new discoveries like this,” said Scott Sheppard, discovery team leader, astronomer at the Carnegie Institution for Science in Washington, DC, said in a press release.

Discovery images of the new asteroid 2021 PH27, taken on the night of August 13, 2021 using the dark energy camera, an instrument mounted on the 4-meter Víctor M. Blanco telescope at the inter-American Cerro Tololo observatory in Chile . (Image credit: CTIO / NOIRLab / NSF / DOE / DECam / AURA / SS Sheppard (Carnegie Institution of Science))

Sheppard and colleagues estimate that 2021 PH27 is approximately 0.6 miles (1 km) wide. Space rock can come from the main Asteroid belt between Mars and Jupiter, then pushed inward by gravitational interactions with one or more planets, according to the researchers.

However, the orbital path of 2021 PH27 is tilted 32 degrees from the plane of the solar system. Such a tilt suggests that it could instead be an extinct comet born in the far outer solar system, then captured in a closer orbit after passing through Mars, Earth, or another rocky planet.

More observations could help solve this mystery, but Sheppard and other astronomers will have to wait a few months to collect more data. 2021 PH27 is now moving behind the sun from our perspective, and it won’t reappear until early 2022, Discovery Team members said.

Mike Wall is the author of “The low“(Grand Central Publishing, 2018; illustrated by Karl Tate), a book on the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.


Arline J. Mercier

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