The orbit of asteroid 2019 LF6 (white) falls entirely within the orbit of Earth (blue). The program was developed by Ye and Wing-Huen Ip of the National Central University in Taiwan and has been responsible for discovering another Atira asteroid dubbed 2019 AQ3.
But 2019 LF6 is doubly rare because it is also relatively big, measuring around a kilometer across. Earth's perihelion is 0.983 AU. Astronomers have only discovered 20 of these up to date. It was named Twilight after the time of day which is the most recommended time for looking for Atira asteroids. It's large, about a kilometre wide.
Only two of the 20 known Atira asteroids are bigger, including 163693 Atira, which is almost 5 kilometres wide.
Caltech researcher Quanzhi Ye says that finding kilometer-sized asteroids is rare.More news: LeBron James Jokingly Teases New "Kung Fu" Look Ahead Of Next Season
'Thirty years ago, people started organizing methodical asteroid searches, finding larger objects first, but now that a lot of them have been found, the bigger ones are rare birds, ' he says.
"Both of the large Atira asteroids that were found by ZTF orbit well outside the plane of the Solar System", said Caltech Professor Tom Prince, a member of the ZTF team. Like the grooves on a vinyl record, most planets align along a flat disk. In its orbit, the asteroid swings out beyond Venus and, at times, comes closer in than Mercury, which circles the sun every 88 days.
The asteroid's elliptical orbit brings the space rock well outside of the plane on which the planets of our solar system orbit, and it gets closer than Mercury does to the sun. It boasts the "shortest year", compared to any other asteroid.
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. Because they're so close to the sun, the best time to find them is around 20 to 30 minutes before sunrise or after sunset. But ZTF is also good at finding asteroids in general.More news: Raspberry Pi 4 Won't Work with Some USB Type-C Cables
Besides the Atira asteroids, ZTF has identified about 100 near-Earth asteroids and about 2,000 orbiting in the Main Belt, between Mars and Jupiter.
NASA has proposed a mission called Near-Earth Object Camera which would look specifically for Atira asteroids.
"It is one of the near-Earth asteroid groups that we don't know much about, since their unique orbits make them hard to observe", Yu told Gizmodo.More news: Backlash after Johnson refuses to guarantee ambassador's future over Trump row