Earth has a new ‘mini-moon’ — and it’s not the first

This view from the Apollo 11 spacecraft shows the Earth rising above the moon's horizonNASA

  • Scientists have spotted a new ‘mini-moon’ orbiting Earth.
  • The visiting space rock has been identified as asteroid 2020 CD3.
  • One of the first mini-moons to be discovered by researchers was 2006 RH120, which circled the planet for 18 months.
The Moon isn’t the only space rock orbiting the Earth. A new mini-moon was spotted circling the planet by a researcher at the Catalina Sky Survey. Between 2 to 3 meters wide, scientists estimate that Asteroid 2020 CD3 has been lingering around for the past three years.

However, this isn’t the first mini-moon that researchers have found.


According to scientists, there is at least one mini-moon circling the planet at any given time — most of them go undiscovered because they’re so small in size.

Not the first mini-moon
In 2016, the National Aeronautics and Space Agency (NASA) reported that another asteroid called 2016 HO3 had been caught in Earth’s gravity.

Bigger than 2020 CD3, it is between 35 to 90 meters wide. When it was initially spotted three years ago, the asteroid had already been around for a century. Scientists estimate that it is likely that it will stick around for many more centuries to come — giving the Earth a grand total of two mini-moons for the foreseeable future.


However, 2016 HO3 was one of many. One of the earliest mini-moons was 2006 RH120, just under a meter in size. According to researchers, it circled the Earth for 18 months between 2006 and 2007.

What do we know about the new mini-moon?
The International Astronomical Union ( IAU) observations “indicate that this object is temporarily bound to Earth,” although it did not issue any estimates how long the new mini-moon will be sticking around.

An orbit model developed by Tony Dunn, an amateur astrophysicist, estimates that 2020 CD3 could be making its exit from Earth’s orbit as early as April.


However, the IAU was able to confirm that the asteroid is not linked to any known artificial objects. “No evidence of perturbations due to solar radiation pressure is seen,” it added.

What would happen if the Earth actually had two moons?
Thankfully, all of the mini-moons spotted so far have been small in size. If a space object, identical to the Moon, was to get trapped in the Earth’s orbit the results wouldn’t be pretty.

Anything a normal moon does, a second moon would exacerbate. So if the original moon dictates tides, a second moon would cause the sea-level to rise suddenly sending the oceans into a violent frenzy.

The tug of war between them for dominance would pull gravity back and forth triggering massive volcanic activity. Like Jupiter’s moon Io — the second moon would be overcome in rivers of lava.

In the long run — a couple of millions of years of repeated volatility — the two moons would eventually collide destroying each other and sending millions of pieces of debris flying into space, including massive chunks towards Earth. Anything that doesn’t get smashed into the surface would get caught in the planet’s gravity.

As of now, the new mini-moon is not something to worry about. While it’s existence has been confirmed, there’s still a lot that scientists hope to uncover in the coming days. Some are hoping that there’s a possibility that the asteroid could get caught in the Moon’s gravity as it flies off, creating a ‘moonmoon’.

See also:
NASA's 'Lucy' is going to travel 4 billion miles to explore seven Trojan asteroids — and an asteroid Moon

The Moon used to have its own shield against the Sun — it died a billion years ago

The world's oldest asteroid struck Earth 2.2 billion years ago triggering one of the first global warming episodes in history