35 Facts About Milky Way


Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye.

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From Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within.

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Milky Way is a barred spiral galaxy with an estimated D25 isophotal diameter of 26.

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The Milky Way has several satellite galaxies and is part of the Local Group of galaxies, which form part of the Virgo Supercluster, which is itself a component of the Laniakea Supercluster.

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The constant rotational speed appears to contradict the laws of Keplerian dynamics and suggests that much of the mass of the Milky Way is invisible to telescopes, neither emitting nor absorbing electromagnetic radiation.

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The oldest stars in the Milky Way are nearly as old as the Universe itself and thus probably formed shortly after the Dark Ages of the Big Bang.

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In western culture, the name "Milky Way" is derived from its appearance as a dim un-resolved "milky" glowing band arching across the night sky.

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Milky Way is visible as a hazy band of white light, some 30° wide, arching the night sky.

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Aristotle himself believed that the Milky Way was part of the Earth's upper atmosphere, and that it was a byproduct of stars burning that did not dissipate because of its outermost location in the atmosphere.

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The Neoplatonist philosopher Olympiodorus the Younger criticized this view, arguing that if the Milky Way were sublunary, it should appear different at different times and places on Earth, and that it should have parallax, which it does not.

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Persian astronomer Al-Biruni proposed that the Milky Way is "a collection of countless fragments of the nature of nebulous stars".

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The Andalusian astronomer Avempace proposed the Milky Way to be made up of many stars but appears to be a continuous image due to the effect of refraction in Earth's atmosphere, citing his observation of a conjunction of Jupiter and Mars in 1106 or 1107 as evidence.

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Proof of the Milky Way consisting of many stars came in 1610 when Galileo Galilei used a telescope to study the Milky Way and discovered that it is composed of a huge number of faint stars.

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Milky Way produced a diagram of the shape of the Milky Way with the Solar System close to the center.

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Milky Way managed to make out individual point sources in some of these nebulae, lending credence to Kant's earlier conjecture.

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Milky Way became a proponent of the "island universes" hypothesis, which held that the spiral nebulae were independent galaxies.

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Milky Way was able to identify some Cepheid variables that he could use as a benchmark to estimate the distance to the nebulae.

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Milky Way found that the Andromeda Nebula is 275,000 parsecs from the Sun, far too distant to be part of the Milky Way.

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The Sun's orbit about the Milky Way is expected to be roughly elliptical with the addition of perturbations due to the Galactic spiral arms and non-uniform mass distributions.

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Galactic quadrant, or quadrant of the Milky Way, refers to one of four circular sectors in the division of the Milky Way.

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Milky Way is one of the two largest galaxies in the Local Group, although the size for its galactic disc and how much it defines the isophotal diameter is not well understood.

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Much of the mass of the Milky Way seems to be dark matter, an unknown and invisible form of matter that interacts gravitationally with ordinary matter.

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The mass distribution within the Milky Way closely resembles the type Sbc in the Hubble classification, which represents spiral galaxies with relatively loosely wound arms.

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In 2010, two gigantic spherical bubbles of high energy gamma-emission were detected to the north and the south of the Milky Way core, using data from the Fermi Gamma-ray Space Telescope.

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Simulation published in 2011 suggested that the Milky Way may have obtained its spiral arm structure as a result of repeated collisions with the Sagittarius Dwarf Elliptical Galaxy.

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Stars and gas in the Milky Way rotate about its center differentially, meaning that the rotation period varies with location.

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The rotation curve of the Milky Way agrees with the universal rotation curve of spiral galaxies, the best evidence for the existence of dark matter in galaxies.

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Milky Way began as one or several small overdensities in the mass distribution in the Universe shortly after the Big Bang 13.

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Since the first stars began to form, the Milky Way has grown through both galaxy mergers and accretion of gas directly from the Galactic halo.

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The Milky Way is currently accreting material from several small galaxies, including two of its largest satellite galaxies, the Large and Small Magellanic Clouds, through the Magellanic Stream.

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The ages of individual stars in the Milky Way can be estimated by measuring the abundance of long-lived radioactive elements such as thorium-232 and uranium-238, then comparing the results to estimates of their original abundance, a technique called nucleocosmochronology.

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Satellite galaxies surrounding the Milky way are not randomly distributed but seem to be the result of a break-up of some larger system producing a ring structure 500,000 light-years in diameter and 50,000 light-years wide.

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In January 2006, researchers reported that the heretofore unexplained warp in the disk of the Milky Way has now been mapped and found to be a ripple or vibration set up by the Large and Small Magellanic Clouds as they orbit the Milky Way, causing vibrations when they pass through its edges.

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Individual galaxies, including the Milky Way, have peculiar velocities relative to the average flow.

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The Milky Way is moving in the general direction of the Great Attractor and other galaxy clusters, including the Shapley supercluster, behind it.

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