Archive · 19 Jan 2026
Mars Once Had an Ocean as Big as Arctic
Scientists have found evidence that Mars once had a big ocean, about the size of the Arctic Ocean on Earth.
This ocean was there around 3 billion years ago.
The researchers looked at pictures of Mars and found places that look like river mouths where water might have flowed into the ocean.
They think this ocean covered a large part of Mars' northern side.
This discovery is important because it shows that Mars might have had the right conditions for life a long time ago.
The scientists used special cameras on space probes to study these areas.
They believe their findings give clear proof that Mars was once a 'blue planet' like Earth.
Mars once had an ocean similar in size to Earth's Arctic Ocean 3 billion years ago.
Evidence of the ocean was found near Valles Marineris, the largest canyon system on Mars.
Researchers identified structures resembling river deltas, indicating a coastline and river mouth.
The ocean stretched across the northern hemisphere of Mars, with its original shape still noticeable despite dusty dunes.
This discovery suggests that Mars could have supported life in its past, highlighting the importance of water for life on planets.
- Who
- Researchers from the University of Bern and INAF – Osservatorio Astronomico di Padova
- What
- Discovery of a vast ocean on Mars, similar in size to Earth's Arctic Ocean, 3 billion years ago
- When
- 3 billion years ago
- Where
- Northern hemisphere of Mars, near Valles Marineris
- Why
- To understand Mars' past and its potential to support life
- Ocean Size
- Similar to Earth's Arctic Ocean
- Location
- Northern hemisphere of Mars
- Time Period
- 3 billion years ago
- Evidence
- River deltas and coastline structures near Valles Marineris
- Researchers
- University of Bern and INAF – Osservatorio Astronomico di Padova
- Tools Used
- CaSSIS camera, ESA's ExoMars Trace Gas Orbiter, Mars Express, NASA's Mars Reconnaissance Orbiter