What if the Earth had rings?


17 Responses to “What if the Earth had rings?”

  1. mdh says:

    My imagination says there is more potential energy in a piece of cm sized space junk at orbital speeds then in a hand grenade.

    Is there a physicist in the house?

    • Anonymous says:

      wgmleslie, you beat me to it. Planetes was a whole series premised on space junk. One of the most clever titles ever (ancient greek for wanderers, which became our word for planets, but the title also refers to the characters). The intro alone packs more space history than your average documentary.


  2. Anonymous says:

    it’s the relative speed that matters, not the overall speed of an object. If I’m moving 16999 mph and something moving 17000 mph in the same direction hits me, i won’t even feel it unless it’s a large object. It certainly won’t puncture anything durable. Anything going significantly slower or faster will find itself in a different orbit fairly quickly, and as far as I know, all that garbage is orbiting the earth in the same direction.

    in short; it’s not quite as bad as they make it sound.

  3. efergus3 says:

    The bad news is, it will once the moon enters the Roche limit and gets torn apart. The good news is that this won’t happen before Xmas.

  4. TheMadLibrarian says:

    If someone comes up with a viable way to clean out space junk from valuable orbital real estate, I’m investing!

  5. Anonymous says:

    The moon will never enter the Roche limit. The moon’s orbit actually is getting farther away from the Earth at 4 centimeters per year.

  6. pjcamp says:

    There is a physicist in the house, and it isn’t the speed that is important, it is the relative speed. Two objects in nearly the same orbit have nearly the same speed so the relative speed is nearly zero and the collision is not nearly so catastrophic.

    The issue comes in when an object is in an elliptical orbit that intersects another orbit. Then, when they meet, they aren’t travelling at anything close to the same speed and collisions can be quite violent.

    The question about the energy content compared to a hand grenade therefore has no real meaning since the absolute velocity of the projectile is irrelevant to computing the energy of the collision. Unless you know the absolute velocity of both object, or their relative velocity, you can’t say.

  7. RedShirt77 says:

    Weren’t both satelites traveling at 42,100 kilometres per hour?

    Wouldn’t the collision just be the difference in their vectors? maybe a few 1,000 kph?

  8. Anonymous says:

    I’m surprised that the commenters who mentioned Planetes didn’t mention the technical term for the “futuristic 12-car pileup”:
    Kessler Syndrome.

  9. valdis says:

    Iridium 33 got nailed at pretty much a right angle, so the relative velocities was pretty close to sqrt(2)*orbital.


    Now, if a 1cm chunk is a hand grenade, then a car sized satellite at sqrt(2)*orbital is….

    And that’s why there’s hundreds of thousands of fragments.

  10. Avram / Moderator says:

    Will the rings at least be pretty?

    • lewis stoole says:

      it had better be pretty after all of the money we spent getting that junk up there.

    • BookGuy says:

      The writer Junot Diaz has often said that pollution makes New Jersey’s sunsets some of the most striking around. By extension, a planetary ring made out of pollution and garbage should be quite stunning. At least from the ground.

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