July 9 (UPI) -- Scientists have identified an asteroid with the shortest known orbital period. The newfound space rock, measuring a kilometer wide, circles the sun once every 151 days.
Upon its closest approach to the sun, the asteroid, dubbed 2019 LF6, moves inside Mercury's orbit. On its aphelion, the portion of the asteroid's orbit farthest from the sun, 2019 LF6 moves beyond the orbit of Venus.
"You don't find kilometer-size asteroids very often these days," Quanzhi Ye, a postdoctoral scholar at the California Institute of Technology, said in a news release.
The discovery was published by the International Astronomical Union's Minor Planet Center.
The space rock is an interior-Earth object, or Atira asteroid, one of 20 asteroids that orbit the sun inside Earth's orbit.
"Thirty years ago, people started organizing methodical asteroid searches, finding larger objects first, but now that most of them have been found, the bigger ones are rare birds," Ye said. "LF6 is very unusual both in orbit and in size -- its unique orbit explains why such a large asteroid eluded several decades of careful searches."
Scientists spotted the unusual asteroid using the Zwicky Transient Facility, or ZTF, a powerful camera at the Palomar Observatory, situated in the mountains between Los Angeles and San Diego. The camera system surveys the sky extremely fast, making an ideal tool for finding asteroids.
"We only have about 20 to 30 minutes before sunrise or after sunset to find these asteroids," Ye said.
The orbital planes of both 2019 LF6 and 2019 AQ3, another Atira asteroid with a short year, are off-kilter from the plane of the solar system.
"This suggests that sometime in the past they were flung out of the plane of the solar system because they came too close to Venus or Mercury," said Tom Prince, a physics professor at Caltech.