Meteor Showers on Mercury

In a new study, Mercury is regularly being hit by a comet which affects the planet's atmosphere to a considerable degree and from this we may be able to discover how this airless body keeps its ethereal envelopes.

Mercury is considered an airless body which has clouds of atomic particles on its surface which is vastly different than the dense atmospheres of both Earth and Mars and is called a 'surface boundary exosphere.'

Researchers recently discovered that there is a peak emission of the element calcium on Mercury which is seen when the planet passes through its perihelion. A comet known as comet Encke has the shortest period of any comet, reaching perihelion in about 3.3 days at 31 million miles from the sun. The orbit of this comet is stable and so it has created a comet dust stream and this affect the emission of calcium from Mercury. This dust spread along the comet's orbit, forming the stream that collides alongside Mercury exactly when the comet does resulting in the observed levels of calcium.

Sources:
http://www.nasa.gov/feature/goddard/mercury-gets-meteoroid-shower-from-comet-encke
http://earthsky.org/space/comet-encke-pelts-mercury-with-meteors