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Thread: Our Galaxy is far bigger, brighter, and more massive than most others

  1. #1
    Join Date
    May 2010
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    66

    Our Galaxy is far bigger, brighter, and more massive than most others

    From Knowable Magazine:

    In this big universe, it’s easy to feel small and insignificant, as if there’s nothing special about our planet, our star, our celestial neighborhood. After all, the sun is just one of hundreds of billions of stars in the Milky Way galaxy. What do we have to brag about?

    Yet astronomers in the know have long realized that our galaxy is exceptional. By size alone, it’s “in the top percentile of all the galaxies that exist,” says Joss Bland-Hawthorn, an astronomer at the University of Sydney who helped compile the galaxy’s vital statistics for a 2016 article in the Annual Review of Astronomy and Astrophysics. He puts the Milky Way’s mass at a hefty 1.0 trillion to 1.6 trillion times that of the sun, outweighing the vast majority of its peers by a factor of 10 to more than a million and greatly outshining them as well.
    Link includes a spectacular video that shows the nearly 60 satellite galaxies that orbit the Milky Way.

  2. #2
    Join Date
    Sep 2006
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    1,822
    Astronomers have also realized that the Sun is larger and more luminous that the great majority of stars. And that the Earth is larger and more massive than the great majority of objects orbiting the Sun. Biologists have known for millennia that humans are larger and more massive than the great majority of living things on Earth.

    What does all this tell us, aside from "power laws are common"? I don't know.

  3. #3
    Join Date
    Feb 2005
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    11,411
    It's Yuge!

  4. #4
    Join Date
    Feb 2009
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    2,205
    In Local Group, Andromeda Nebula is bigger than Milky Way. And there are 60 smaller galaxies, starting with Triangulum and Big Magellanic Cloud.
    How does the combined mass of the 60 smaller galaxies compare to the combined mass of the 2 big ones?

  5. #5
    Join Date
    Feb 2006
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    542
    Recent publications suggest that the Milky Way is about 1.2 x 10^12 solar masses (Watkins et al, 2019),
    while the mass of the Andromeda galaxy is only about 0.8 x 10^12 solar masses (Kafle et al, 2018).

    See

    Evidence for an Intermediate-Mass Milky Way from Gaia DR2 Halo Globular Cluster Motions
    Watkins et al.
    https://arxiv.org/abs/1804.11348

    and

    The Need for Speed: Escape velocity and dynamical mass measurements of the Andromeda galaxy
    Kafle et al.
    https://arxiv.org/abs/1801.03949
    Selden

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