From Mars, we move even closer to home and take a look at Earth’s latest minimoon, a newly discovered asteroid with the designation 2020 CD3. Astronomers used the Lowell Discovery Telescope to analyze this second minimoon, and their work is published in The Astronomical Journal.

A minimoon is a tiny asteroid that gets captured by Earth’s gravity, orbits our planet for a while, and then gets flung back out into the solar system. The first minimoon discovered here was found back in 2006.

CD3 was discovered early this year, and scientists quickly rallied to observe and understand our new satellite while they had the chance. Measurements indicate that CD3 is a natural satellite, made of silicate, about 1-1.5 meters in diameter and that it came within about 13,000 kilometers of Earth.

While this is only the second minimoon found, the expectation in the astronomical community is that we will find more of these small, transient bodies once the Rubin Observatory is complete. Again, understanding minimoons will help understand the evolution of our solar system and possibly even provide targets for robotic exploration. That sounds really cool to me, y’all.

More Information

Lowell Observatory press release 

“Establishing Earth’s Minimoon Population through Characterization of Asteroid 2020 CD3,” Grigori Fedorets et al., 2020 Nov. 23, Astronomical Journal (preprint on arxiv.org)