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Re: Planetary Rings around Earth

>|http://cnn.com/TECH/space/9902/26/lunar.chip/index.html
>
>In an attempt to kill two birds with one stone:-) I correlated these two
>recent discoveries.
>Ron posted the above Chip Off the Old Moon message on March 1, 1999 and it
>turns out they named it Asteroid 3753. 

No, sorry, these are not the same objects.  Asteroid 3753 Cruithne does
have an orbit similar to Earth's, but is it larger and has a different
orbit from the object mentioned in the CNN article.  The object in the CNN
article matches the orbit of an Atlas-Agena upper stage that was used
to launch Ranger 6 in 1964.

>The existence of this alone may suggest that
>it is a reminent from a ring and there may be more lurkers out there.

Its existence just means we have more space junk up there than we care to
admit.

>I recall asking the list why it
>was assumed that all asteroids approach
>Earth at super high velocity.  

Because they originate from the asteroid belt.  

>I used the example of a pool
>ball just barely dropping into the pocket.  I don't have the message and
>it's probably in the missing archives, but I wonder if that is the
>explanation for how this proposed catching of an asteroid and subsequent
>breaking up happened or is there another explanation?

Orbit capture requires the object to be slowed down near its closest approach
to another body.  This can happen either by a collision with another
satellite or the main body itself.  If there is no slowdown, the object
will just continue to flyby the Earth.   We've done orbit capture with 
spacecraft, but it requires precise timing and placement, and
happens very rarely on its own in the solar system.  Over the span
of 4.5 billion years, there are only about 8 satellites that may have been
captured in orbit around a planet, so it is a very rare event.  

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