Did Earth Have A Two Hour Day?

New theory explains why we have a 24-hour day and how the moon was formed.

18:17 01 November 2016

A new research has claimed that when the moon was formed 4.5 billion years ago, the Earth was left with a two-hour day. Scientists have long debated how the moon was formed and a couple of theories suggest that it was due to a “giant impact” or more violent collision.  

 

The latest computer model says that there was a high energy collision that left a mass of vaporised and molten material from which the Moon and Earth formed, with Earth’s axis pointing towards the Sun and spinning with a two-hour day. Over millennia, the moon has receded from the Earth and the rotation slowed to our current 24-hour day. 

 

An alternative theory says that angular momentum was dissipated through tidal forces and the moon receded from the Earth. After tens of millions of years, the moon continued to slowly move away from Earth until it reached the Cassini transition. 

 

Professor Sarah Stewart, of California University in Davis, said that the new theory explains the moon's orbit and composition based on a single, giant impact at the beginning. 

 

She said: "One giant impact sets off the sequence of events."