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Thread: Ten things that I did not know about our Galaxy

  1. #1

    Ten things that I did not know about our Galaxy

    Yes, I admit it. I didn't know the following:

    http://www.badastronomy.com/bablog/2...ky-way-galaxy/

    1. Our galaxy is a "bar" galaxy. There is a 27 light-year long bar of stars in the middle, the two ends of which are the source of the spiral arms.

    2. At the very center of our bar, there is a monsters supermassive black hole. Stars that are close to that center are rotating at a screaming speed (thousands of km per second). This is because the mass of the black hole is four million times the size of our sun. We can't see it because it is a "black" hole.

    3. Our galaxy eats other smaller galaxies. We are currently eating a couple.

    4. Our galaxy (the Milky Way) is the big guy on the block, called the Local Group. We are bigger than other members of the Local Group, i.e. Andromeda and Triangulum. There are three dozen other galaxies in our "local group" but most are little dinky dwarf galaxies.

    5. However, the big group Virgo cluster, a collection of about 2000 galaxies.

    6. The Milky Way that we can see is only 0.000003% of the galaxy.

    7. 90% of the Milky Way is invisible or Dark Matter. I knew about Dark Matter of course but did not think that it is 90% of the mass of the galaxy.

    8. The number of stars in the spiral arms are not much greater than the number of stars between the spirals. Starts ar constantly passing in and out of the spirals. The spirals just indicate where there are traffic jams of stars.

    9. The Milky way is warped. Although it is a flat disk of 100,000 light-year diameter and a few thousand light-years thick, proportionately about the same as stacking four DVD's on top of each other, it bent due to the gravitational infleunce of two satellite galaxies that orbitus.

    10. Andromeda takes up quite a bit of our sky. On clear moonless nights, you can see if 4+ degrees across, eight times the apparent size of the moon in the sky. The two galaxies are approaching each other at 200 km/sec. It will be a cosmic collision in a couple billion years.

    It is true... I didn't know this. Did you?

    Wise.

  2. #2
    Quote Originally Posted by Wise Young
    7. 90% of the Milky Way is invisible or Dark Matter. I knew about Dark Matter of course but did not think that it is 90% of the mass of the galaxy.
    I'm working on a fun program right now - we're building a satellite to do a full sky survey in the mid-infrared. One of its (many) goals is to find brown dwarfs, which are part of the missing dark matter.

    Quote Originally Posted by Wise Young
    It is true... I didn't know this. Did you?
    Most of them :-).

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