A black and white photo of Edwin Hubble, seated at his desk. He is wearing a tweed jacket and smoking a pipe (goals) that he is holding in his left hand. Hubble's body is facing away from the camera, toward the desk, but his head is turned to look at the photographer. His right hand holds a pencil and rests on a stack of papers on the desk.

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1. Robert McNees (mcnees@mastodon.social)'s status on Sunday, 20-Nov-2022 19:36:05 UTC Robert McNees

   Astronomer Edwin Hubble was born #OTD in 1889.

   Hubble is best known for combining galactic distance measurements with Slipher’s redshift data to obtain a linear relation between distance and recession velocity. This is now understood as evidence for an expanding universe.

   Before that, Hubble used Henrietta Swan-Leavitt's period-luminosity relation for Cepheid variable stars to establish spiral nebulae as separate galaxies situated outside the Milky Way.