Recent discoveries of over 15,000 kilometers of ancient riverbeds on Mars reveal that the planet was wetter in the past than previously thought, with nearly 10,000 miles of these features found in the southern highlands.

These geological features, including inverted channels and sinuous ridges, date back over 3 billion years and suggest they were formed by regional rainfall or snowfall, indicating sustained water activity.

Data from orbital instruments like CTX, MOLA, and HiRISE helped map these river systems, which extend hundreds of kilometers and showcase the extensive reach of ancient water flows.

Focusing on Noachis Terra, a region in the southern highlands, researchers uncovered complex networks of meandering tributaries and inverted channels, challenging earlier assumptions of a dry environment.

Findings presented at the Royal Astronomical Society's 2025 meeting suggest that surface water persisted around 3.7 billion years ago during the Noachian-Hesperian transition, pointing to a more active and dynamic ancient Mars.

The widespread presence of these ridges across various terrains supports the idea that Mars experienced long-lasting warm and wet periods, which could have supported significant geological processes.

The interconnected ridge systems imply relatively stable and long-lived wet conditions, contradicting theories that Mars was predominantly cold and dry.

While Noachis Terra has been less studied due to fewer valley networks, the focus on fluvial ridges provides new evidence of ancient surface water, indicating that water was more widespread than previously believed.

Some riverbeds and valleys stretch over 100 miles, indicating periods when water was abundant on the surface, shaping large valleys and erosion features.

These findings, to be presented at the same meeting, suggest that surface water existed for a significant time around 3.7 billion years ago before atmospheric loss transformed Mars into its current arid state.

The disappearance of surface water is linked to Mars's waning magnetic field, which allowed solar wind to erode its atmosphere, though some water may still be hidden beneath the surface.

Overall, these discoveries highlight a more complex and wetter past for Mars, with evidence pointing to sustained water activity that shaped its ancient landscape.