Compositio4 - Composition The Hermian exosphere consists of...

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Composition The Hermian exosphere consists of a variety of species originating either from the Solar wind or from the planetary crust . [3] The first constituents discovered were atomic hydrogen (H), helium (He) and atomic oxygen (O), which were observed by the ultraviolet photometer of the Mariner 10 spacecraft in 1974. The near-surface concentrations of these elements were estimated to vary from 230 cm −3 for hydrogen to 44,000 cm −3 for oxygen, with an intermediate concentration of helium. [3] In 2008 the MESSENGER probe confirmed the presence of atomic hydrogen, although its concentration appeared higher than the 1974 estimate. [4] Mercury's exospheric hydrogen and helium are believed to come from the Solar wind, while the oxygen is likely to be of crustal origin. [3] Ca and Mg in the tail The fourth species detected in Mercury's exosphere was sodium (Na). It was discovered in 1985 by Drew Potter and Tom Morgan, who observed its Fraunhofer emission lines at 589 and 589.6 nm. [5]
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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