[Lexicon]

To return to the origional topic:

The earth's orbit slowing down is part of the earth-moon-sun orbital system and conservation of angular momentum (Jupiter also has an influence). The short of it is, because of this dynamic, the earth moves slightly away from the sun over time which causes its orbit to slow down. This is a good thing, due to the fact that the sun is slowly heating up over time.

The longer explanation is that the tidal forces between the earth and the moon slow down the earths rotation which reduces its angular momentum, but angular momentum must be conserved so the earth moves farther from the sun (creating a longer angular arm). Moving away from the sun means the earth's orbit must slow down to remain stable (but not as much as the angular arm increases angular momentum).

Makes sense?