Many planets have multiple moons, but Earth has a solitary satellite orbiting it. However, for a brief period of time, Earth has a “mini-moon" to keep it company. The extra-planetary body is actually an asteroid called 2020CD3. Its diameter is between 1.9-3.5 m, which is roughly a size between a cow and a hippopotamus.
The new ‘moon’ has been temporarily bound to the Earth. It was discovered on Tuesday by Minor Planet Centre at International Astronomical Union. The centre is the official organization for naming, studying, and analysing all minor planetary and extra-planetary bodies in the solar system.
One of the scientists involved with the discovery, Kacper Wierzchos, recently tweeted about the ‘moon’.
BIG NEWS (thread 1/3). Earth has a new temporarily captured object/Possible mini-moon called 2020 CD3. On the night of Feb. 15, my Catalina Sky Survey teammate Teddy Pruyne and I found a 20th magnitude object. Here are the discovery images. pic.twitter.com/zLkXyGAkZl— Kacper Wierzchoś (@WierzchosKacper) February 26, 2020
The caption read, “BIG NEWS (thread 1/3). Earth has a new temporarily captured object/Possible mini-moon called 2020 CD3. On the night of Feb. 15, my Catalina Sky Survey teammate Teddy Pruyne and I found a 20th magnitude object. Here are the discovery images.”
(2/3) The object has just been announced by the MPC and its orbit shows that it entered Earth's orbit some three years ago. Here is a diagram of the orbit created with the orbit simulator written by Tony Dunn: pic.twitter.com/2wsJGtexiO— Kacper Wierzchoś (@WierzchosKacper) February 26, 2020
(3/3) The object has a diameter between 1.9 - 3.5 m assuming a C-type asteroid albedo. But it's a big deal as out of ~ 1 million known asteroids, this is just the second asteroid known to orbit Earth (after 2006 RH120, which was also discovered by the Catalina Sky Survey).— Kacper Wierzchoś (@WierzchosKacper) February 26, 2020
He explained that the discovery was a monumental event as there are nearly 1 million known asteroids but this is only the second in the known history of space studies to orbit Earth. Before this, 2006 RH120 was known to have orbited Earth briefly. That was also a discovery of the Catalina Sky Survey.
But what causes these mini-moons or asteroids to the Earth’s orbit? It’s a combination of the Earth’s gravity with the moon and sun’s gravitational pull. These forces simultaneously combined create a kind of irregular orbit on which the moon or asteroid can adhere to.
According to the astronomer, the mini-moon probably entered the Earth’s orbit around three years ago. As for the future, it can be expected to stay around from October 2020 to May 2021.
So far, little is known about the asteroid. However, during the next year, it is expected to come closer to the Earth. The closeness should give a chance to make clearer and more detailed observations and help assess its origin.
The weather.com reported it is likely the ‘mini-moon’ is human-made. Paul Chodas, director for Centre for Near-Earth object Studies at NASA, has made this suggestion. He thinks it could be Surveyor 2 lunar lander—an uncrewed NASA moon mission that was launched via the Atlas Centaur-D rocket on September 20, 1966.