Jesse Leonard Greenstein (October 15, 1909 - October 21, 2002) was an American astronomer. With Leverett Davis, Jr, he demonstrated in 1949 that the magnetic field in our galaxy is aligned with the spiral arms. His theoretical work, with Davis, was based the conclusion just reached by William A. Hiltner that the recently detected polarisation of starlight was due to scattering off interstellar dust grains aligned by a magnetic field. Read more