Space Physics

Earth's extensive hydrogen corona

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Science  15 Mar 2019:
Vol. 363, Issue 6432, pp. 1188-1189
DOI: 10.1126/science.363.6432.1188-g

Dissociation of water in Earth's atmosphere produces hydrogen atoms, which escape into space through a combination of thermal and nonthermal processes. These hydrogen atoms resonantly scatter light from the Sun, producing an ultraviolet glow around Earth called the geocorona. Baliukin et al. analyzed ultraviolet observations taken by the Solar and Heliospheric Observatory spacecraft. They found that the geocoronal emission extends to at least 100 Earth radii, almost twice the distance to the Moon. This greater-than-expected extent of the geocorona indicates that nonthermal processes are launching hydrogen atoms from Earth's upper atmosphere at high speeds.

J. Geophys. Res. Space Phys. 10.1029/2018JA026136 (2019).

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