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1750 – Thomas Wright discusses galaxies and the flattened shape of the Milky Way and speculates nebulae as separate. [11] 1755 – Immanuel Kant drawing on Wright's work conjectures that our galaxy is a rotating disk of stars held together by gravity, and that the nebulae are separate such galaxies; he calls them Island Universes.
The earliest known galaxies existed by about 380 Ma. Galaxies coalesce into "proto-clusters" from about 1 Ga (redshift z = 6 ) and into galaxy clusters beginning at 3 Ga ( z = 2.1 ), and into superclusters from about 5 Ga ( z = 1.2 ). See: list of galaxy groups and clusters, list of superclusters. Reionization: 200 Ma ~ 1 Ga (Exact timings ...
Spiral galaxies are quite thin, dense, and rotate relatively fast, while the stars in elliptical galaxies have randomly oriented orbits. The majority of giant galaxies contain a supermassive black hole in their centers, ranging in mass from millions to billions of times the mass of the Sun. The black hole mass is tied to the host galaxy bulge ...
Many galaxies are thought to have black holes at their active centers. The Milky Way's central black hole, known as Sagittarius A* , has a mass four million times greater than the Sun. As of March 2016, GN-z11 is the oldest and most distant observed galaxy with a comoving distance of 32 billion light-years from Earth, and observed as it existed ...
Galactic astronomy – deals with the structure and components of our Galaxy and of other galaxies. High energy astrophysics – studies phenomena occurring at high energies including active galactic nuclei, supernovae, gamma-ray bursts, quasars, and shocks. Interstellar astrophysics – study of the interstellar medium, intergalactic medium ...
Spiral galaxy UGC 12591 is classified as an S0/Sa galaxy. [1]The Hubble sequence is a morphological classification scheme for galaxies invented by Edwin Hubble in 1926. [2] [3] It is often known colloquially as the “Hubble tuning-fork” because of the shape in which it is traditionally represented.
NASA has captured what it looks like when two galaxies collide. The image is of Arp 299, about 140 million light years away from Earth, and has been merging for millions of years.
1180s (decade) – Robert Grosseteste described the birth of the Universe in an explosion and the crystallisation of matter. He also put forward several new ideas such as rotation of the Earth around its axis and the cause of day and night.