Astronomers have spotted 2019 LF6, which is about one kilometer wide and boasts the "shortest" year of any known asteroid, circling the sun every 151 days, according to the California Institute of Technology.
This rare rocky body is one of the 20 known Atira asteroids, those whose orbits fall entirely into that of the Earth.
"Nowadays, we do not often find as many as one kilometer-sized asteroids," said Quanzhi Ye, a postdoctoral researcher at Caltech, who discovered the LF6 2019 via the Zwicky Transient Facility, a camera of the day. 39, Palomar observatory of the school, which scans the sky in search of objects. "Thirty years ago, people began to organize methodical searches for asteroids, first looking for larger objects, but now that most of them have been found, the larger ones are rare birds. "
Asteroids are hard to spot because astronomers only have 20 to 30 minutes before or after sunset to find them, Ye said.
"The LF6 is very unusual both in orbit and size, and its unique orbit explains why such a large asteroid has escaped decades of careful research," Ye said.
In its orbit, the LF6 2019 moves beyond Venus and sometimes approaches the sun compared to Venus, which bypasses it every 88 days.
The ZTF team has discovered another Atira asteroid, the 2019 AQ3, which revolves around the sun every 165 days.
In addition to Atira asteroids, ZTF has identified about 100 near-Earth asteroids and about 2,000 in orbit in the main belt between Mars and Jupiter.