APOD: 2020 July 8 - Mercurys Sodium Tail

Good morning, Rallypoint. Today's Astronomy Picture of the Day (APOD) is titled "Mercury's Sodium Tail." I had no idea Mercury had sodium in its atmosphere. Or that the sodium would produce a 'tail' (much like a comet) as Mercury orbits the Sun. But so it does. Astronomers predicted a tail back in the 1980s, and it was confirmed in 2001. Many tail details were revealed in multiple observations by NASA's robotic MESSENGER spacecraft that orbited Mercury between 2011 and 2015. This image of Mercury was taken in May 2020 from Italy.