The Astronomy Thread

Discussion in 'Science and Technology' started by xsited1, Mar 8, 2011.

  1. xsited1
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    xsited1 Agent P

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    Post all things Astronomy whether political or not.

    I'll start.

    Lowell Observatory in Flagstaff, Arizona, sometimes has open nights for the public. Back in the 90s, I once saw Saturn through their main telescope, the 24" Alvan Clark Refracting Telescope. The view was breathtaking.

    $LowellTelescope.jpg

    $saturnPic1.jpg

    Lowell Observatory
     
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  2. American Horse
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    American Horse AKA "Mustang"

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    Collisions of stars are incredibly unlikely; they occupy such a relatively miniscule volume of space, that even when a pair of galaxies collide, few if any of their constituent stars crash into each other.

    Objects in space like planets are much more likely to collide if they orbit each other or orbit a common primary object. In our own solar system Venus doesn’t deserve to smash into anything, since it’s orbit is so perfectly circular.
    But Mercury is not so well behaved. Its orbit – already the most lopsided – wildly changes shape. Influences from faraway Jupiter will eventually make its path so elliptical that it will swing out to Venus. Then those two worlds MAY collide.

    Here's a fair approximation of what that might look like.
    Mercury's diameter is 40 percent that of Venus

    [​IMG]
     
    Last edited: Mar 8, 2011
  3. Trajan
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    Trajan conscientia mille testes

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    interesting..what the timeline on that?
     
  4. Trajan
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    Trajan conscientia mille testes

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    the Egyptians figured out the circumference of the Earth by using a known height,a ruler and digging a hole...anyone ( minus google) know how?
     
  5. American Horse
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    American Horse AKA "Mustang"

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    It's indefinite because Mercury's orbital plane wobbles taking it both N & S of the orbital plane of Venus. It could even miss Venus and approach a collision with Earth instead. If that path is followed and there's near-hit versus a direct hit with Earth, it could even be ejected by the slingshot effect from the solar system, that being the remotest likelihood.

    Edit: I can see how Earth's diameter can be determined by those tools by taking measurements in two locations a known distance apart if they lay on a north/south line but I don't see the need for digging a hole in the ground unless it be to produce a leveling method for measuring a shadow on a plane.
     
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  6. Mr. H.
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    Mr. H. Diamond Member

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    They dug the hole to the center of the earth, measured it and multiplied by 2. The result was then multiplied by pi.

    Hey- here's a nifty site: a new astro pic every day. :thup:

    Astronomy Picture of the Day Archive
     
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  7. xsited1
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    xsited1 Agent P

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    During the years from 1758 to 1782 Charles Messier, a French astronomer (1730 - 1817), compiled a list of approximately 100 diffuse objects that were difficult to distinguish from comets through the telescopes of the day. Discovering comets was the way to make a name for yourself in astronomy in the 18th century -- Messier's first aim was to catalog the objects that were often mistaken for comets.

    Fortunately for us, the Messier Catalog became well known for a much higher purpose, as a collection of the most beautiful objects in the sky including nebulae, star clusters, and galaxies.

    SEDS Messier Database

    Here's M42 in the constellation Orion:

    $M42bestRes.jpg

    Messier
     
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    Last edited: Mar 9, 2011
  8. American Horse
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    American Horse AKA "Mustang"

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    Here's a "free copy" of a Tool - the SimSolar - Solar System Simulator - with a visual of the positions of all the planets, earth/moon on the current date or any date between 2/23/1915 and 2/25/2086

    here's a small gif image of what it looks like elliptically;
    it can expand to a full overhead computer screen view

    [​IMG]
     
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  9. asterism
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    asterism Congress != Progress

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    I thought it was actually two holes (wells) and Eratosthenes new the distance between them.
     
  10. asterism
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    asterism Congress != Progress

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    Stellarium, and awesome (and free) program for just about all platforms.

    Stellarium

    It's a personal planetarium with the ability to see what the sky looks like at any time and location on the planet.
     
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