(Mars is tilted on its axis like Earth, so it has similar seasonal changes, including an autumnal equinox when the Sun crosses Mars' equator from the northern to the southern hemisphere).
(Mars; is tilted; on its axis like Earth) (it; has; similar seasonal changes, including an autumnal equinox) (the Sun; crosses; Mars' equator)
Mars it the Sun
is tilted has crosses
on its axis like Earth
similar seasonal changes, including an autumnal equinox
Mars' equator