Atmospheric sounding using Earth-based occultations

The observation of Earth-based stellar occultations by solar system planets and satellites has been used for decades to retrieve information on the physical properties of their atmospheres. From the variations of the stellar flux during ingress and egress and, in some favourable cases, from the central flash, one can infer the vertical density, pressure and temperature profiles around the half-light level (typically in the range of a few μbars), as well as zonal wind regimes and the presence of hazes. Earth-based occultations have been successfully applied to all planets and satellites surrounded by an atmosphere, and have delivered unique and significant information that are often complementary to the results obtained by planetary space missions. The great improvement of the stellar catalogues provided by the Gaia astrometric space mission has drastically enlarged the capabilities of the stellar occultation method, which appears especially promising for probing the tenuous atmospheres of distant objects of the solar system.

This article is part of the theme issue ‘Major advances in planetary sciences thanks to stellar occultations’.