Thanks to astronomers and their constant search for new bodies moving throughout our solar system, we know about a lot of asteroids. Many of them have long, elliptical orbits around our Sun, swinging through our system — sometimes making close passes of Earth along the way — around the Sun and then back out again.

Now, researchers have spotted an asteroid that never really ventures all that far from the Sun, even at its further point. The object, known as 2019 LF6, completes an orbit of our star every 151 days, and comes far closer to the Sun than even Mercury.

LF6 travels in an elliptical orbit that takes it within Mercury’s orbit, around the Sun, and then back out past the orbit of Venus. It never gets close to Earth, and nobody knew it existed until now. The asteroid is estimated to be around a kilometer in width, which makes it even more remarkable that it’s remained hidden for this long.

“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,” Tom Price of Caltech explains. “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.”

Asteroids that orbit particularly close to the Sun and never travel out past Earth into the deeper reaches of the solar system are often difficult for astronomers to spot. They have to dedicate their observation resources to very narrow windows of time just before sunrise and after sunset, hoping to spot the objects before the Sun’s light overwhelms the imaging instruments.

LF6 has the shortest “year” of any known asteroid, and while it isn’t of particular interest to scientists as a near-Earth object, it’s a special discovery.