3) These spiral nebulae were also observed spectroscopically, which means the light coming from them was broken up into individual wavelengths, recorded and analyzed.

Galaxies shine in a rainbow of emissions from gas, dust, and stars. Each of these building blocks emits light at specific ...

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.

[+] spiral nebula M101, now known as the Pinwheel galaxy. This data was disputed at the time and was later shown to be incorrect, but not before many drew conclusions based upon it.

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

He argued that the analysis of light from spiral nebulae indicated that they were clusters of stars (with similar features to the spectrum of light from the Milky Way itself).

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.

A “nebula,” the Latin word for cloud, ... Originally, astronomers thought they were one and the same and thought of objects like the Andromeda Galaxy as a spiral nebula within our galaxy.

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.