Astronomers using the Catalina Sky Survey telescope have discovered our new cosmic 'friend': a cosmic body temporarily captured by our planet's gravity.
Officially named 2020 CD3, a small space rock composed of carbonaceous rock with a diameter of 1.9 to 3.5 meters. But – the trajectory of the rock indicates that it has been in orbit for about three years.
The coastal neighborhood is a relatively busy area with asteroids streaking past. The exact numbers, however, are unclear. This number is estimated to be in the millions, but as of February 25, the number has been discovered: 22,211.
Kacper Wierzchos / Twitter
This is because asteroids are really small, we don't know where they are (so we don't know where to look), and they usually don't emit much light, even when they reflect sunlight.
These briefly captured space stones are either sent directly into the atmosphere, where they burn up upon entry, becoming spectacular fireballs; or they 'glide' in a partial orbit before being swept into deep space.
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 Wierzchos (@WierzchosKacper) February 26, 2020
According to a supercomputer simulation that included 10 million virtual asteroids in the analysis, only 18,000 were captured in near-Earth orbit.
So not only are they difficult to spot, but they are also very rare. There were several candidates for the title of mini moons, but only one was confirmed – an asteroid called 2006 RH120, which orbited the Earth for about a year from 2006 to 2007.
So 2020 CD3 is something big. Not only because its rarity makes it something famous, but also because mini moons provide an opportunity to explore asteroids.
Here's an animated GIF of our new mini-moon 2020 CD3, discovered by @WierzchosKacper. Rotating frame keeps the Earth / Sun line stationary. Orbital elements courtesy of IUA MPEC. https://t.co/dok3jn3G9hhttps://t.co/x1DXWLq2vm pic.twitter.com/O3eRaOIYjB
– Tony Dunn (@ tony873004) February 26, 2020
Sending a spacecraft to asteroids is costly and time consuming, and often requires tremendous distances to be covered. If the asteroid orbits the Earth, that would make it a much easier target.
Most likely too late to send a mission to 2020 CD3. According to the orbital simulation, our little friend will be out of Earth's orbit by April 2020. However, it is possible that the simulation is incorrect, so observation continues.
In any case, by studying our mini moon's strange looped orbit, we can learn more about how these objects are captured by the Earth, and how we might look for them in the future.
