Near Earth Objects
There have actually been several
Armageddon style collisions predicted. And
although none have actually come close enough to
worry Earth NASA still keeps track of every
object that is calculated to come close enough
to cause issues. In June of 2013 there
were a total of 10,000 Near Earth objects on
NASA's watch list. In fact as recent as
November 5th of this year three more asteroids
that are large enough and close enough to be
potentially hazardous have been
discovered.
NASA also keeps track of all the space debris
floating around our dearly beloved planet.
Which, thank you F=ma is ANY trash or debris
that we have ever tossed out up there.
Once we push it out the door it floats until
another force interacts with it. Since the
only other force out there that is large enough
and close enough to act on it is the gravity of
the Earth, all of the trash out there falls into
an orbit around us. For example here is a
picture of the NASA interactive satellite viewer
showing just the debris from the Cosmos 2251
satellite after it collided with the Iridium 33
satellite.
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