Edwin Hubble: observations that placed Andromeda beyond the Milky Way
Edwin Hubble was an astronomer whose observations helped establish that galaxies exist beyond the Milky Way.
Edwin Hubble was an astronomer whose observations helped establish that galaxies exist beyond the Milky Way.
Observation changed the picture
NASA’s biography describes Hubble’s work with the 100-inch Hooker Telescope at Mount Wilson Observatory. In 1923 he resolved stars in the object then commonly called the Andromeda Nebula. Cepheid variable stars provided a way to investigate its distance.
The distance evidence showed that Andromeda was a separate galaxy rather than an object within the Milky Way. Hubble also developed a system classifying galaxies by their visual shapes.
A person and a telescope
NASA’s account connects Hubble’s later observations with the relation between galaxy distance and recession. The space telescope bearing his name honours this astronomical legacy; it is a different instrument from the ground-based Hooker Telescope used in his work.
A headline using Hubble may refer to the astronomer, the telescope or a distance–recession relation. Identifying which meaning is intended is the first step toward understanding the claim.
Read a discovery as a chain of evidence
Separate the observed object, the measurement method and the conclusion. In this case, variable stars supplied distance evidence used to establish a galaxy beyond our own. This is more informative than saying someone simply looked through a telescope and discovered the universe.
For an original note-taking exercise, create two columns headed person and instrument. Place Edwin Hubble in the first and distinguish the Hooker and Hubble Space Telescopes in the second. Then record which observations belong to which instrument. This prevents a modern mission’s results from being mistakenly attributed to the historical astronomer.
The article is an introductory historical profile. It does not supply a current Hubble-constant estimate or suggest that every nearby galaxy recedes from the Milky Way. Those scientific questions require more specific data and context than a short biography.
Publication disclosure
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Frequently asked questions
Which ground-based telescope did Hubble use at Mount Wilson?
The 100-inch Hooker Telescope.
Was Andromeda shown to be part of the Milky Way?
No. The distance evidence established it as a separate galaxy.