Apparently, a visiting mini-moon, now dubbed as 2020 CD3, has been orbiting Earth for about three years now and we didn't even know anything about it until recently. 
Astronomers discovered the tiny asteroid in Tuscon, Arizona on 15th February 2020.

Kacper Wierzchos, a researcher with the Catalina Sky Survey at the University of Arizona's Lunar and Planetary Lab, took to Twitter to make the announcement. 

According to reports, the object measures about 6 to 11 feet across, which is around the same size as a small car. 

This is a big deal because out of over 1 million space rocks, this is only the second asteroid known to orbit Earth, after the 2006 RH120 asteroid.

The 2006 RH120 remained within the earth’s gravitational pull between September 2006 and June 2007 before it managed to wriggle free.

Moon
Source: twitter.com

If researchers are to be believed, there are chances that the asteroid got caught up by the Earth's gravitational pull and has been circling our planet ever since. 

Even Twitter was amazed by this new discovery:

However, astronomers have also said that the new mini-moon orbit isn't stable, which means, eventually, the 2020 CD3 might catapult itself away from Earth, just like the 2006 RH120 asteroid.