Quirks & Quarks

Will the Earth ever have a 'dark side'

The Earth could become tidally locked to the Sun over many billions of years.
The orbit of Earth is synchronised with the rotation of the moon, which explains why we only see one side of the moon. So you'll never see what appears in this artist's rendition. (Guillaume Preat, Pixabay)

This week's question comes from Richard Atkinson of Thunder Bay who asks, "We know there is no 'dark side of the moon' but there is only one side that always faces Earth and that is because the orbit is exactly synchronized to the rotation of the moon. This, I believe, is called 'tidal lock' and can happen when one planet orbits another. 
Can the the orbit of the Earth ever become locked in this way, to the Sun? "  

Dr. Christa Van Laerhoven, a post-doctoral fellow in the Physics and Astronomy Department at the University of British Columbia explains that most of the large moons in the solar system are tidally locked to their planets, including the Earth's moon.

Tidal lock occurs when rotation and orbit of the moon are synchronized.

This explains why we only see one side of the moon on Earth. The Earth could eventually become tidally locked with the Sun — leaving the Earth with a true "dark side," but this could only happen in the absence of our moon, which has a stronger tidal affect on the Earth than the Sun does.