John Gallagher III

John (Jay) S. Gallagher III is an American astronomer.
He was raised near New York city and received his undergraduate education at Princeton University. He performed his graduate work at the University of Wisconsin–Madison, and was awarded a Ph.D in 1972. After graduating he held positions at the National Optical Astronomy Observatory and at the University of Illinois, and was the director of the Lowell Observatory. He is currently a Professor of Astronomy at the University of Wisconsin–Madison and the Editor of the Astronomical Journal.
Gallagher's major scientific contributions include a review article he wrote along with Sandra Faber in 1979 that convinced most astronomers that dark matter was real. In the 1980s, with Deidre Hunter, he made the first substantial studies of dwarf irregular galaxies. Gallagher has made major contributions towards our understanding of star formation in galaxies, the formation and evolution of low mass galaxies and stellar nova.