This research concerns continuation of precise astronomical measurements related to solar variability, the relation between solar activity and planetary weather, and variations in the transparency of the Earth's atmosphere. New evidence for a relationship between solar output and planetary "weather" comes from the planet Neptune, whose global albedo has indicated cyclic variations associated with solar cycle. Telescopic and Voyager spacecraft images combined with photometry relate the brightness variations to transiting stratospheric clouds of frozen methane. This work will include further multispectral continuum and methane-band photometry and collaborative infrared imaging of Neptune, plus comparative measurements of Titan and Uranus which also vary in brightness during solar max 91, to test competing solar-weather theories involving UV driven photochemistry and cosmic-ray induced nucleation. A series of indirect solar brightness measurements derived from photometry of the Galilean satellites of Jupiter will also be completed. The 1976-1992 photometry encloses the 1980-1989 era of precise solar radiometry by the Solar Maximum Mission (SMM) and will test the veracity of a reported 0.4% solar brightness increase between 1976 and 1978. Finally, using multicolor nighttime stellar and daytime solar photometry, a long series of aerosol and ozone extinction measurements will be made to look for systematic trends and diurnal variations.
