Faithful companion

Small asteroid orbits Earth as a “quasi-moon”

The orbits of Earth (purple) and asteroid 2016 HO3 (yellow)

(Bild: NASA/JPL (Grafik), thinkstockphotos.de)

Astronomers have discovered a small asteroid that accompanies the Earth on its path around the sun. The celestial body with a diameter of around 40 to 100 meters orbits the Earth again and again. Researchers from the US space agency NASA assume that the mini asteroid named 2016 HO3 has been accompanying our planet for 100 years and will continue to orbit it for several centuries to come.

The rock is held in its orbit by the Earth's gravitational pull. It moves a maximum of 100 times as far away from the Earth as the moon is from the Earth and never comes closer than 38 times the distance between the Earth and the moon (see video).

"You could say that this small asteroid and the Earth are dancing together," says Paul Chodas from NASA's Near Earth Objects (NEO) Observing Program.

The asteroid was discovered at the end of April with the University of Hawaii's Pan-STARRS PS1 telescope in Haleakala National Park. According to NASA, it had a predecessor: 2003 YN107 orbited the Earth in a similar path. About ten years ago, however, the lump disappeared into the depths of space.

The Pan-STARRS telescope PS1 on Haleakala in Hawaii

(Bild: PS1SC/Rob Ratkowski)

No danger for the next 200 years
In contrast, 2016 HO3 appears to be a faithful companion - and a harmless one at that, as Lindley Johnson from NASA's Planetary Defense Coordination Office says: "We don't see any danger of 2016 HO3 colliding with Earth for the next 200 years. Unfortunately, we cannot see further into the future."