Earth Picks Up An Extra Moon — For Now
A pair of astronomers have discovered a second moon circling the Earth, thanks to observations by the Catalina Sky Survey in Tucson.
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
How many moons does Earth have?
It depends on when you ask.
For months or years, a Volkswagen-sized rock has circled our world roughly every four months.
Astronomers believe the object, unpoetically labelled "2020 CD3," is one of many space rocks that zip past us; this one just happened to get caught in our gravity.
Other objects are known or suspected to engage in a gravitational dance with Earth, but are not satellites per se.
But another temporary moon did visit 14 years ago: a fridge-sized asteroid called 2006 RH120.
Like its predecessor, CD3 eventually will leave Earth behind — a mere planetary pit stop on its journey through the solar system.