1) what would our lives be like if earth had a highly eccentric orbit around the sun?
2) consider objects whose orbits lie entirely within that of the earth (i. e., never reaches 1 au). can any such object have an orbital period > 1 year? if so, give an example of such an orbit. if not, explain why not.
3) now consider objects which have part of their orbit inside 1 au and part outside of 1 au. can any such object have a period p > 1 year? if so, give an example of such an orbit. if not, why not? same thing for p < 1 yr.
4) the most massive solar system object beyond neptune is not pluto, but a body discovered thirteen years ago, known as eris (and now, officially, neither are planets). eris has a semimajor axis a = 68 au. how many times will the earth go around the sun when eris does so once?