Mars had gushing rivers flowing along its surface in the past billion years, finds new study. The unexpected discovery raises important questions about how a planet with so little sunlight and atmosphere stayed warm enough to host not just a little surface water, but fast-flowing rivers.

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Mars had gushing rivers flowing along its surface in the past billion years, finds new study. The unexpected discovery raises important questions about how a planet with so little sunlight and atmosphere stayed warm enough to host not just a little surface water, but fast-flowing rivers.