The super moon appears in the sky in Cairo, Egypt, October 17, 2016.
A new model for how the moon formed in the distant past suggests a dramatic, violent collision that altered the Earth s tilt and spin rate.
Today, the Earth is tilted just over 23 degrees compared to its orbital plane around the sun.
"Evidence suggests a giant impact blasted off a huge amount of material that formed the moon," Douglas Hamilton, a professor of astronomy at the University of Maryland and a co-author of the new study, said in a statement.
"This material would have formed a ring of debris first, then the ring would have aggregated to form the moon.
But this scenario does not quite work if Earth's spin axis was tilted at the 23.5 degree angle we see today."