Skip to Content
Space

Earth just gained a new mini-moon—but it won’t be around for long

February 27, 2020
2020 CD3
2020 CD3
2020 CD3The international Gemini Observatory/NSF’s National Optical-Infrared Astronomy Research Laboratory/AURA/G. Fedorets

A pair of astronomers just discovered a “mini-moon” asteroid within Earth’s orbit. And it turns out it may have been orbiting us for years, undetected until now. 

How was it found: The asteroid, called 2020 CD3 (also known as C26FED2), was discovered by the Catalina Sky Survey at the University of Arizona on February 15. The two researchers responsible for the discovery held off on announcing their findings while they confirmed exactly what 2020 CD3 was and what its orbit looked like. Its small size and peculiar orbit helped hide it well from astronomers. 

Mini-moons are formally known as Temporary Captured Orbiters (TCO)—objects that are currently looping the planet, but will eventually shove off and resume their trip around the sun. CSS previously found a TCO that stumbled into Earth’s orbit in 2006, before exiting the following year. 

Tell me more about the rock: There’s honestly not much to tell yet. It’s estimated to between 6.2 and 16.4 feet in diameter. It seems to have entered Earth’s orbit three years ago. Its calculated trajectory so far suggests it will exit Earth’s orbit in April. "It cannot be ruled out that the object is artificial," says Theodore Pruyne, one of the researchers who made the discovery. "At this moment, with the observations we have, we can only say that it is a probable 'mini moon,'" and not just an old satellite or other human-made object.

What’s next: A lot more observations. Spotting a mini-moon is pretty rare. The goal behind CSS is to track 90% of all objects larger than 460 feet. Finding such small objects is basically an accident. And there are probably many more mini-moons orbiting Earth that we just haven’t spotted yet.

Deep Dive

Space

supermassive black hole at center of Milky Way
supermassive black hole at center of Milky Way

This is the first image of the black hole at the center of our galaxy

The stunning image was made possible by linking eight existing radio observatories across the globe.

SpaceX Starship
SpaceX Starship

How SpaceX’s massive Starship rocket might unlock the solar system—and beyond

With the first orbital test launch of Starship on the horizon, scientists are dreaming about what it might make possible— from trips to Neptune to planetary defense.

Mapping the atmosphere on Mars can help advance science on our own planet

The Emirates Mars Mission is monitoring and measuring the climate and atmosphere of the red planet, but this effort also helps promote and advance science at a national level.

Photograph, Seine et Marne on march the 6th 2021 at night. Taurus constellation. On this image we can see the effect of the movements of artificial satellites through the sky. On the left we can see the planet Mars, on the right the famous stars cluster the Pleiades (M45). From the bottom right the luminous trail of the satellite STARLINK-1269, and from the top the luminous trail of the satellite STARLINK-1577
Photograph, Seine et Marne on march the 6th 2021 at night. Taurus constellation. On this image we can see the effect of the movements of artificial satellites through the sky. On the left we can see the planet Mars, on the right the famous stars cluster the Pleiades (M45). From the bottom right the luminous trail of the satellite STARLINK-1269, and from the top the luminous trail of the satellite STARLINK-1577

SpaceX just lost 40 satellites to a geomagnetic storm. There could be worse to come.

Increasing solar activity could play havoc with mega-constellations like Starlink in the coming years.

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.