The atmosphere of Mercury is a tenuous exosphere that contains varying elements. The elements contained in Mercury’s exosphere are helium, hydrogen, oxygen, sodium, calcium, potassium and water vapor. The comet-like tail that is seen on the end of the planet is created by atmospheric gasses that are pushed by solar light. Sodium is the primary element located in its tail. Mercury’s tail extends very far from the planet. Other elements in its tail include traces of calcium and magnesium but these do not extend as far as the sodium tail do.

Before 1974, the existence of an atmosphere in Mercury was a topic that produced heated debates. Because Mercury is too close to the Sun, it was very hard to study. It wasn’t until the Mariner 10 spacecraft discovered the exosphere of Mercury’s atmosphere. The data gathered by the Mariner 10 spacecraft confirmed that only an exosphere existed on Mercury and is similar to the Moon in having no atmosphere. On 2008 the Messenger spacecraft found magnesium in its exosphere.

Mercury’s exosphere varies in temperature. It all depends on the location and the type of matter on the surface. The calcium atoms are some of the hottest elements on this planet, with temperatures reaching 12,000 k – 20,000 K. Sodium atoms are also very hot with the ones located on the equator having temperatures reaching 750 – 1500 K. The ones on the poles vary from 1500-3500 K. Atomic hydrogen is relatively lower than these elements with temperatures around 420 K.

Most of the particles in the exosphere escape into space. This implies that the elements in the exosphere are constantly being supplied by its constituents. The source of the hydrogen and helium in the exosphere is the Solar Wind. Other atoms and molecules come from the crust of Mercury itself. The main supply of the elements found in Mercury’s exosphere are from vaporized surface material caused by meteors hitting its surface, energetic charged particles that are emitted by the Solar Wind and the desorption of atoms of alkali metals.

Mercury – 2nd Messenger Flyby