The Oort Cloud: Made of Comets, Has Massive Diameter


Not only fun to spell, fun to say as well!  Oort.  Not too many words begin with more than one o!  The Oort Cloud is named after Dutch astronomer Jan Hendrik Oort.

In 1950 Oort speculated that the Solar System was surrounded by a vast spherical cloud of comets.  He thought this would explain why we still see comets today.  He figured that since comets are comprised primarily of water, ammonia, and methane they are extremely volatile and would not last long orbiting the sun.  For anyone who has ever seen the long tail of a comet (which is the comet material being blown away by the sun) you know what he was thinking about!  There had to be a reserve of them out beyond the direct gravitational pull of the individual planets and even the sun itself.  In fact, the Oort Cloud defines the end of the sun’s gravitational influence.oort-cloud

The Oort Cloud was most likely formed as part of the original protoplanetary disk which became our solar system.   It is almost a light year distant from the Sun which would put it almost one quarter of the way to the nearest star to us, Proxima Centauri.

Although no one has directly observed the Oort Cloud, it is believed to contain billions of icy cometary bodies.  These icy bodies will occasionally be influenced by the gravity of a distant, passing star and become a comet.

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7 Responses to “The Oort Cloud: Made of Comets, Has Massive Diameter”

  • lilikindsli says:

    4VW8fI I want to say – thank you for this!


  • d says:

    whats comets diameter?


    Greg - Staff Writer replied:

    See our post on Comet Shapes.


  • jedi1010 says:

    If no one has directly observed the Oort Cloud, has there been some indirect observance or other evidence to suggest its existence? Could there be another explanation for the source of comets?


  • the twin says:

    What are the three known objects that have been discovered that might possibly be objects in the closest edge of the Oort Cloud?


  • katesisco says:

    About the Ort cloud; could it be:
    1) the sun twin gone nova?
    2) Proxima Centauri’s twin gone nova?
    3) It appears our solar system has a cellular type membrane of magnetism/plasma and this is why we have a ‘orange rind’ of debris around it?
    4) any orbiting body by definition is orbiting around something so where is the something our proposed orbiting body that disturbs the Ort Cloud is orbiting around?
    5) Why is it we can see novas in Casseopia and not next door in the Ort Cloud?


  • dani808 says:

    whats the Oort clouds structure ? or what is it made of ?


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