EXPLAINED: Tale of two moons

Ishaan Gera
While earth is surrounded by quasi moons or asteroids, these usually follow U-shape orbit around the sun.

Galileo was one of the first to draw a telescopic drawing of the moon. Until then moon was supposed to be round and spherical and smooth, but Galileo noted that the surface had craters and mountains. But that was the extent of Galileo’s discovery, as he was limited by the technology of his time. Such has been the case with the latest discovery by two astronomers from the Catalina Sky Survey. On February 15, Kacper Wierzchos and Theodore Pruyne, stationed at the Mount Lemmon Observatory, Arizona, US, discovered an asteroid orbiting the earth. Another moon so to say.

So, does earth have another moon?
In a manner of speaking, it does. While it is not uncommon for planets to have more than one moon-Saturn just pipped Jupiter to the spot with 82 moons-Earth has been believed to have just the one. While the 2020 CD3 may be classified as moon, it will not be orbiting the earth for long as it is expected to leave the orbit soon.

What is 2020 CD3?
2020 CD3 is an object, the size of a small car, that was found revolving the earth in February. While earlier it was thought that it is space debris, scientists observing the body found it to be something else. The composition of the body is not known till date. It is also not clear when it arrived and started orbiting the earth, what the astronomers know is that it will leave the orbit in two weeks.

Is this the first body to revolve the earth?
No, in 2006 and 2007, a moonlet designated as 2006 RJH120 was found orbiting the earth. Although astronomers thought that it was piece of Apollo 12 mission, later on it was found to be part of asteroid belt. The rock is expected to return in 2028.

So, what makes 2020 CD3 special?
While earth is surrounded by quasi moons or asteroids, these usually follow U-shape orbit around the sun. The only bodies to revolve around the Earth besides the moon are Kordylewski clouds. The 2020 CD3 is supposed to break away in a matter of weeks, but until then, Earth has two moons.

Is there room to find more moons?
The Earth does have some objects revolving around it from time to time, but they usually break free from the orbit. Coming back to the Galileo point, 2020 CD3 is not really unique, but we have been limited by our technology and rarely know when we get such occurences. With Vera Rubin laboratory in place and Near Earth Object Surveillance Mission being developed, we will be able to track such bodies more accurately in the future.

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