Discussion » Statements » Rosie's Corner » A Mug friend mentioned two things I'd never even heard about. OORT CLOUD and KUIPER BELT. Know what they are?
RosieG

A Mug friend mentioned two things I'd never even heard about. OORT CLOUD and KUIPER BELT. Know what they are?

OORT CLOUD
A giant spherical layer of icy objects surrounding the rest of our solar system

KUIPER BELT
A donut-shaped ring of icy objects around the sun. Pluto is a Kuiper Belt object.

Comets originate from there apparently.

Now here's something astonishing to me.

Comet C/2013A1 Siding Spring passed by Mars in 2014 and won't return to the inner solar system for 740,000 years! Now HOW DO "they" KNOW THAT? How can "they" possibly KNOW that?

Posted - February 13, 2021
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Responses


  • 3719
    The more they find, the  more wonderful it is.

    Calculating orbits is a lot simpler than we might think. It might be beyond my mathematical skill but the laws governing them have been known for nearly 400 years. The more difficult part is making the necessary measurements from observations. The planetary laws of motion were established by the German astronomer Johannes Kepler as far back as the 17C. This is one of his remarks:

    "I demonstrate by means of philosophy that the earth is round, and is
    inhabited on all sides; that it is insignificantly small, and is borne
    through the stars."

    (The study of nature was called "philosophy" then. The word "science" was not yet invented.) I wonder what Kepler would say if he could come back now and see that recent photo a NASA probe took from somewhere far out in the Solar System, looking back towards the Sun. It was just an engineering test but the NASA staff published it because they were so startled and impressed by what it shows - they realised one tiny, bright dot against the star-studded blackness is the Earth, far away in the distance.

    It's not so much that comets come from the Kuiper Belt as that their orbits' further limits are in it. They are small, and their orbits around the Sun are huge, very elongated ellipses so they spend most of their time too far away to be visible to us. Also as they recede from the Sun they become colder, losing their tails of ice evaporated by the Sun's warmth, making the lonely little things even less visible.  
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      February 13, 2021 12:22 PM MST
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  • 113301
    I appreciate your thoughtful and informative reply Durdle. How do they KNOW it is 740,000 years away? How can something like that be predicted? Boggles my mind is what it does! Who will be around to verify/validate? Why not say one million years or 35,000? Seriously. :)
      February 14, 2021 2:50 AM MST
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