The Minor Planet Centre has just announced that our planet has been orbited by a second moon for the past three years or so. Designated 2020 CD3, the object is extremely faint and small (1-6 m across) — and won’t be with us for much longer. 2020 CD3 is estimated to be only between one and six meters across. Image credit: Jonny Lindner. 2020 CD3 was first spotted by U.S. astronomers Theodore Pruyne and Kacper Wierzchos using a 1.52-m (60 inch)...