Sulfuric acid, H2SO4, has been a known constituent of the atmosphere of
Venus since the 1974 study by
Hovenier of the polarization of clouds on Venus,
which built upon earlier work by
Pollack et al. and others. It is now well-established
that the dense
clouds and haze layers on the planet are composed
of concentrated sulfuric acid.
To date, sulfuric acid has not been detected in interstellar clouds. In 1981,
Hollis et al. reported their search for two
degenerate lines of H2SO4 in a variety of sources but found no evidence for it anywhere
they looked. The related species SH,
H2S have all been detected in
interstellar sources. Scappini et al.
suggested that sulfuric acid might be present in hydrated form trapped in icy grain mantles.