Discovery of the fastest orbiting asteroid in the solar system.

An asteroid recently found zips around the sun faster than any of her known relatives.

The Rock of Space, known as 2021 PH27, completes a tour around our star every 113 days of Earth's determined discoverers. It is the shortest orbital period of any known solar system object except for the planet Mercury, which only takes 88 days to orbit the sun.

However, 2021 PH27 travels on a much more elliptical path than Mercury does and therefore gets considerably closer to the sun — about 12.4 million miles (20 million kilometers) at closest approach, compared to 29 million miles (47 million km) for the solar system's innermost planet.

During these close solar transitions, the 2021 PH27 surface becomes hot enough to melt lead – about 900 degrees Fahrenheit (500 degrees Celsius), the discovery team estimates. These deep dives into the sun's gravity shaft also mean that the asteroid undergoes the greatest general relativity effects of any known solar system object. These effects are manifested by a slight oscillation in 2021 of the elliptical orbit of PH27 around the sun that the team observed.

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

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

The team was able to pin down the asteroid's orbit over the next few days, thanks to further observations by the DEC and the Magellan Telescopes at the Las Campanas Observatory in Chile, as well as smaller scopes in Chile and South Africa operated by the Las Cumbres Observatory.

The 2021 PH27 push postponed some of the observations programmed with these instruments, but the rework was worthwhile, team members said.

"Though telescope time for astronomers is very precious, the international nature and love of the unknown make astronomers very willing to override their own science and observations to follow up new, interesting discoveries like this," discovery team leader Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington, D.C., said in a statement.

Sheppard and colleagues estimate the 2021 PH27 to be about 0.6 thousand (1 km) wide. The rock in space may have come from the main asteroid belt between Mars and Jupiter, and then was pushed inward by gravitational interactions with one or more planets, say the researchers.

However, the 2021 PH27 orbital trajectory is inclined by 32 degrees concerning the solar system plane. Such a high inclination suggests it might instead be an extinct comet that was born in the far outer solar system, then captured into a closer orbit passing by Mars, Earth, or another rocky planet.

Other observations may help resolve the 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 will not reappear until early 2022, the members of the discovery team said.