The Valles Marineris is the longest and deepest canyon in the Solar System! It is located on “the red planet”, Mars! This canyon could go from the East coast to the West coast of the U.S. if it was on Earth. The formation of the Valles Marineris is still unknown, but it is related to some processes that may have happened on Mars millions of years ago! Even though it’s origins are unknown, the Valles Marineris is still the longest and deepest canyon in the Solar System!!