it takes the moon to make one 360 orbit around the earth Seasons on earth are caused by . . . the fixed tilt of the earth's spin axis with respect to the distant, background stars the fixed tilt of the earth's north polar axis toward the sun the changing distance between the earth and the sun, because our orbit is elliptical our own atmosphere: northern hemisphere plant life uses more CO 2 starting in fall, which enhances the greenhouse effect;
(our orbit; is; elliptical) (northern hemisphere plant life; uses; more CO 2 starting in fall) (more CO 2; enhances; the greenhouse effect)
our orbit northern hemisphere plant life more CO 2
is uses enhances
elliptical
more CO 2 starting in fall
the greenhouse effect