Re: How does the earths constant weight change affect its orbit?

Charlie,

Almost nothing we do has any effect on the mass of the Earth. Cutting down trees, having babies, etc, make no difference -- we are just moving matter around, not removing it from the Earth. And the amount of matter we do remove from the Earth is very tiny - see this answer for a calculation illustrating this.

At least to a first approximation, changing the Earth's mass wouldn't change its orbit anyway. The orbit of something around the Sun does not depend on its mass, as long as that mass is much smaller than that of the Sun (the Earth's mass is about three millionths that of the Sun). Of course, changing the Earth's mass would affect the Moon's orbit, which would have a small effect on the Earth-Moon system's orbit around the Sun and could also affect things like the tilt of the Earth's axis.

The Earth's orbit probably has varied over the hisroty of the solar system -- there are scientists who try and figure out what these variations were and correlate them with things like geological records of climate change. But as far as I know, the variation in Earth's orbit is supposed to be caused by the small gravitational effects of the other planets, not by anything `internal' to Earth. Try our search engine - look up "orbit climate" - to find out more.

Pauline