Mar 3, 2020 - Science

Earth adopted a new "mini-moon"

Gemini Observatory's image of 2020 CD3.

Gemini Observatory's image of 2020 CD3. Photo: NSF/AURA/G. Fedorets

A likely "mini-moon" found orbiting Earth last month is moving away from our planet now, but it could be a harbinger of new small moons to come.

Why it matters: Objects like this one — which is thought to be a washing machine-sized asteroid captured by Earth's gravity — could allow scientists to one day study space rocks without needing to head all the way out to the asteroid belt.

  • "Because they have such similar orbits to the Earth ... they don't take as much energy to get to, on average, so they could be good places for us to send spacecraft," asteroid researcher Amy Mainzer told Axios.

What's happening: The mini-moon, named 2020 CD3, has likely been orbiting Earth for the past year, but it's taken until now for scientists to spot the small object.

  • The Catalina Sky Survey discovered 2020 CD3 on Feb. 15, marking only the second time in history that an object like this has been spotted.
  • According to NASA, the mini-moon has orbited Earth at least three times, with orbital periods that swing between 70 and 90 days, bringing it as far away as four times the distance between the Earth and our Moon.
  • The object's closest approach to Earth was about 25,000 miles from the planet's surface on Feb. 13.
  • 2020 CD3 is now expected to leave Earth behind early this month, escaping the planet's gravitational pull and moving into orbit around the Sun.

What's next: Scientists think there is likely some kind of mini-moon orbiting Earth at any given time.

  • Observatories expected to come online in the next few years will likely be able to spot far more of these objects than scientists are able to study today.
  • Space-based small satellite missions might even be able to one day meet up with a mini-moon to get a close-up look at it.

Go deeper: NASA racing to get astronauts to the moon in four years

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