May 11, 2012, 12:00 pm - 1:00 pm

May 11, 12:00 pm - 1:00 pm

Mercury's Tenuous Atmosphere

Dr. Carl Schmidt, Boston University

Both ground and space-based observations of Mercury are inherently difficult due to the planet’s proximity to the Sun, leaving it the least well studied of the terrestrial planets. Recent data from the MESSENGER and STEREO spacecraft, combined with advances in ground-based imaging technology, reveal a very active environment and one unique among planets within our solar system. The atmosphere and magnetosphere are highly coupled to their space environment, and dynamic on very short timescales. Solar wind and magnetospheric plasma can directly impact the surface through the thin atmosphere in the absence of a conductive ionosphere. The tenuous atmosphere originates from the planet’s surface through a variety of mechanisms, but the relative contribution of each is uncertain. Moreover, each varies spatially and temporally. An overview of atmospheric sources and losses is presented, in which data and modeling of the bright sodium emission are used since Na can serve as a proxy for other constituents. Insights gained though combining several datasets and numerical modeling will be discussed — with particular attention to the exosphere’s dependence upon the solar wind and planetary magnetic field.