2b95aab6_Marvel_Moon___Background__On_Moonless_Earth
[0] Seasons [On Companion Earth] Earth’s large Moon stabilizes the variation of its tilt so that it “wobbles” only about 3° over a cycle of about 41,000 years [Implication] Only the hardiest bacteria or other simple life forms can endure the drastic climate changes [On Moonless Earth] 
Gravitational pull of the giant planets causes Earth's tilt to vary wildly over the eons between 0 and 80°
Marvel Moon - Background
On Moonless Earth