Hale-Bopp (C/1995 O1)

Hale-Bopp was an exceptionally bright and long-visible comet that passed Earth in 1997, remained visible to the naked eye for a record 18 months, and possessed two distinct bright blue ion and white dust tails.

A spacecraft launched in 2013 that has been studying Mars' upper atmosphere, solar wind interaction, and atmospheric loss processes, helping scientists understand how the Red Planet lost most of its air and water over billions of years.

The first spacecraft to visit Mercury conducted three flybys between 1974-1975, capturing over 2,800 photos and revealing previously unknown features including the planet's scarred, cratered surface and weak magnetic field.