On the umbra-penumbra area ratio of sunspots

Astrophysical quantities

D. Lynden-Bell · Journal of Atmospheric and Terrestrial Physics · 1974 · 1.6K citations

Observations of Solar Irradiance Variability

R. C. Willson, S. Gulkis, M. A. Janssen et al. · Science · 1981 · 404 citations

Natural Sciences, Astronomy, Earth Sciences +17

On the appearance of magnetic flux in the solar photosphere

C. Zwaan · Solar Physics · 1978 · 197 citations

Natural Sciences, Astronomy, Physics +14

The physics of sunspots

L. E. Cram, John H. Thomas · Nature · 1981 · 149 citations · Full text

Natural Sciences, Astronomy, Physics +10

The effects of sunspots on solar irradiance

H. S. Hudson, S. Silva, M. F. Woodard et al. · Solar Physics · 1982 · 121 citations

Natural Sciences, Astronomy, Earth Sciences +12