... Aurora and Orion . ... Mapping Mars . ... Orbiting about once every two hours at an altitude of over 200 miles, instruments onboard MGS now regularly explore the Martian surface and atmosphere. ... The Vernal Equinox occurs Saturday, March 20, marking the first day of Spring for the Northern Hemisphere. ... The Moon almost ruined this photograph. During late March and early April 1997, Comet Hale-Bopp passed nearly in front of the Andromeda Galaxy. ... Hydrogen, Helium, and the Stars of M10 . ...