The orbit of asteroid 2019 LF6 (white) falls entirely within the orbit of Earth (blue). Image via NASA/JPL-Caltech.
On July 8, 2019, Caltech astronomers announced their discovery of an unusual asteroid with the shortest year known for any asteroid. The rocky body, dubbed 2019 LF6, is about half a mile (1 km) in size and circles the sun roughly every 151 days.
2019 LF6 is one of only 20 known Atira asteroids, which are objects whose orbits fall entirely within Earth’s path around the sun. That is, their orbit has an aphelion (farthest point from the sun) smaller than Earth’s perihelion (nearest point to the sun). In its orbit, 2019 LF6 swings out beyond Venus and, at times, comes closer to the sun than Mercury, which circles the sun every 88 days.
Quanzhi Ye, a postdoctoral scholar at Caltech, discovered 2019 LF6. He said in a statement:
You don’t find kilometer-size asteroids very often these days. 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. LF6 is very unusual both in orbit and in size – its unique orbit ...