Science

Earth has a second moon right now

At the 15. In February, astronomers at the Catalina Sky Survey Telescope, located in Tucson, Arizona, discovered asteroids, a celestial body that orbits the earth like the moon. That reports the astro portal “EarthSky.org”.

“Shortly after my teammate Teddy Pryne and I discovered the object, we determined the orbit and found that it was caught by gravity, ”reports Kacper Wierzchos to the Tagesspiegel. It was still unclear whether it was a natural or artificial object, such as space junk. He then called it “possible mini moon”.

Maximum 3.5 meters tall

As the Minor Planet Center now reports to the International Astronomical Union, more than 50 observations would mean the existence of the body name 2020 CD3 confirmed. According to Wierzchos, the companion is an asteroid with a size between 1.9 and 3.5 meters.

He is currently circling the earth at 2.6 times the moon. Analysis of the orbit suggests that the chunk entered an earth orbit three years ago. The modeled orbit has little in common with the usual ellipse of the large moon, it is more of a wild back and forth that only gives a hint of the connection to Earth.

Nicht

Not “hardly bigger than a house”, like the “Little Prince”, but even smaller is the asteroid (green), which is currently similar … Photo: Catalina Sky Survey

Just a small chunk – but it is “a big deal”, writes Wierzchos on Twitter that out of around a million known asteroids only the second has been identified that orbits the earth.

The other, “2006 RH 120 ”, was also discovered by the Catalina Sky Survey and orbited 2006 / 2007 four times the earth before he left again. The object, which is a few meters tall, is currently on a circuit around the sun.

Also 2020 CD3 is described by the Minor Planet Center as an “object that is temporarily bound to the earth”. This happens when the orbit of asteroids near Earth is disturbed in such a way that they remain close to Earth for a few months or years, orbiting them several times as seen from Earth.

This orbit is not stable in the long term, which is why astronomers do not speak of a “second moon”. This also applies to 2020 CD3, which according to Wierzchos will leave Earth's orbit in about a month and return to a sun-bound orbit.

Not every short-term moon can escape the earth again

Not every “temporary mini-moon” manages to escape, it can also on earth end up. This probably happened in August 2016. At that time, a meteor descended over South Australia.

Researchers led by Patrick Shober from Curtin University in Perth reconstructed the event and found that the object was rather slow at only eleven kilometers per second before it burned up.

You suspect that it was an asteroid that had also previously been captured by the Earth's gravity and thus slowed down. They reported about it 2019 in the “Astronomical Journal”.

In the future, such events could also be predicted thanks to survey telescopes, write Shober and his team.

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