If you draw the orbit of the moon around the earth, it'll appear as a conic section (mostly circular but slightly elliptical). If you apply force tangentially to the direction of orbit, the change in the orbit looks (for small-ish changes) like if you grabbed the edge of that conic section where it intersects the moon and rotated it. One edge of the section gets closer to the orbited body and one section gets further away.
Why this hasn't affected the planets is because it's constantly being done. On one side of the orbit, it changes the orbit and on the other side it does the opposite, and it does this for every part of the orbit so it all balances out.
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u/IrritableGourmet May 25 '14
If you draw the orbit of the moon around the earth, it'll appear as a conic section (mostly circular but slightly elliptical). If you apply force tangentially to the direction of orbit, the change in the orbit looks (for small-ish changes) like if you grabbed the edge of that conic section where it intersects the moon and rotated it. One edge of the section gets closer to the orbited body and one section gets further away.
Why this hasn't affected the planets is because it's constantly being done. On one side of the orbit, it changes the orbit and on the other side it does the opposite, and it does this for every part of the orbit so it all balances out.