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The young Sun and the atmosphere and photochemistry of the early Earth

Giampapa, M. S.; Imhoff, C. L.; Canuto, V. M. +2 more

The origin and evolution of the Earth's early atmosphere depend crucially on the dissipation time t_N of the primitive solar nebula, SN. Using different theories of turbulence, we estimate that for a 0.1 M_solar SN, t_N is 2.5-8.3Myr. Because accretion times are usually much longer, we conclude that most planetary acc…

Tentative confirmation of an aurora on Uranus

Owen, T.; Caldwell, J.; Encrenaz, Th. +2 more

There have been three recent reports of the detection of Lyman-alpha radiation (due to atomic hydrogen, H, at wavelength 1,216 A) from Uranus by means of the International Ultraviolet Explorer (IUE) satellite. The interpretations of these results differ. Two reports conclude that there is a strong aurora on Uranus, but the third concludes that the…