Hubble worked hard, taking images of spiral nebulae every clear night and looking for the telltale variations of Cepheid variables. By the end of 1924, he had found 12 Cepheids in M31.

Over subsequent months, Hubble examined other spiral nebulae as he searched for more Cepheids with which to measure distances. Word of Hubble's observations was spreading among astronomers.

A third category – nebulae with spiral structure – particularly intrigued astronomers. The Andromeda nebula, M31, was a prominent example. It’s visible to the naked eye from a dark site.

SEASON OF THE HARVEST MOON The Spiral Nebulae About Andromeda -- Movements and Occultations of the Planets. Share full article. Sept. 2, 1900. ...

Slipher, working with a small telescope equipped with ingenious spectroscopes, had found that spiral nebulae move at high speeds, mostly away from us — which is usually regarded as Hubble’s ...

THE extraordinary velocities of recession which are derived from the shift toward the red of the spectral lines of remote galaxies have led to much scepticism of the interpretation of this shift ...

IN “Our Astronomical Column” of NATURE of August 2, reference is made to Prof. Perrine's letter on Prof. Lindemann's spiral nebula hypothesis which appeared in the Observatory for July. As ...

Greetings stargazers. Many scientific terms are very specific, but the term nebula is, well, nebulous. In a very generic sense, it simply means a fuzzy thing. But there are a wide variety of ...

The second key was the work of Vesto Slipher, who had investigated the spiral nebulae, before Hubble's Andromeda discovery. These bodies emit light which can be split into its component colors on ...

The headline read: Finds Spiral Nebulae are Stellar Systems: "Dr. Hubbell Confirms View That They Are 'Island Universes'; Similar to Our Own." On Sunday November 23, 1924, ...