page_title: Messier 87
section_title: Identification as a galaxy
hierarchical_section_title: Messier 87 / Observation history / Identification as a galaxy
caption_attribution_description: English: Galaxies are very important fundamental building blocks of the Universe. Some are simple, while others are very complex in structure. As one of the first steps towards a coherent theory of galaxy evolution, the American astronomer Edwin Hubble, developed a classification scheme of galaxies in 1926. Although this scheme, also known as the Hubble tuning fork diagram, is now considered somewhat too simple, the basic ideas still hold...Čeština: Galaxie jsou velmi důležitými základními stavebními kvádry vesmíru. Některé galaxie jsou jednoduché, jiné jsou velmi složitě členěné. Jedním z prvních kroků ke vzniku soustavné teorie o vývoji galaxií bylo klasifikační schéma galaxií, které v roce 1926 vyvinul americký astronom Edwin Hubble. Takzvaná Hubbleova ladička byla později rozšířena o další typy galaxií, původní myšlenka však stále přetrvává.
context_page_description: Messier 87 is a supergiant elliptical galaxy with about 1 trillion stars in the constellation Virgo. One of the most massive galaxies in the local universe, it has a large population of globular clusters—about 12,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs, traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers.
  The French astronomer Charles Messier discovered M87 in 1781, and cataloged it as a nebula. M87 is about 16.4 million parsecs from Earth and is the second-brightest galaxy within the northern Virgo Cluster, having many satellite galaxies. Unlike a disk-shaped spiral galaxy, M87 has no distinctive dust lanes. Instead, it has an almost featureless, ellipsoidal shape typical of most giant elliptical galaxies, diminishing in luminosity with distance from the center. Forming around one-sixth of its mass, M87's stars have a nearly spherically symmetric distribution. Their population density decreases with increasing distance from the core.
context_section_description: In 1922, the American astronomer Edwin Hubble categorized M87 as one of the brighter globular nebulae, as it lacked any spiral structure, but like spiral nebulae, appeared to belong to the family of non-galactic nebulae. In 1926 he produced a new categorization, distinguishing extragalactic from galactic nebulae, the former being independent star systems. M87 was classified as a type of elliptical extragalactic nebula with no apparent elongation (class E0).
  In 1931, Hubble described M87 as a member of the Virgo Cluster, and gave a provisional estimate of 1.8 million parsecs (5.9 million light-years) from Earth. It was then the only known elliptical nebula for which individual stars could be resolved, although it was pointed out that globular clusters would be indistinguishable from individual stars at such distances. In his 1936 The Realm of the Nebulae, Hubble examines the terminology of the day; some astronomers labeled extragalactic nebulae as external galaxies on the basis that they were stellar systems at far distances from our own galaxy, while others preferred the conventional term extragalactic nebulae, as galaxy then was synonym for the Milky Way. M87 continued to be labelled as an extragalactic nebula at least until 1954.
caption: In Hubble's galaxy classification scheme, M87 is an E0 galaxy
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