An astronomical explanation for Mercury's apparent retrograde motion in our skies: the inner planet appears to retrace its steps a few times per year. Every planet does this, every year. In fact, there is a planet in retrograde for 75% of 2020 (not unusua

An astronomical explanation for Mercury's apparent retrograde motion in our skies: the inner planet appears to retrace its steps a few times per year. Every planet does this, every year. In fact, there is a planet in retrograde for 75% of 2020 (not unusua