Scientists are investigating a massive, enigmatic scar on Mars whose origins remain a mystery.

Dubbed Aganippe Fossa, this feature stretches approximately 600km (373 miles) across, longer than the Grand Canyon, and is located on the lower flank of Mars’ colossal volcano, Arsia Mons.

Initially identified in 1930, the scar has now been observed up close for the first time by the ESA spacecraft Mars Express.

Described as a dark, irregular groove cutting through the terrain, Aganippe Fossa has steep walls and is situated amidst the Tharsis region, known for its vast Martian volcanoes like Olympus Mons, the New York Post has reported.

Arsia Mons itself measures 435km (270 miles) in diameter and rises over 9km (5.5 miles) above the surrounding plains, exceeding even Earth’s tallest dormant volcano, Ojos del Salado.

Written by B.C. Begley