For the first time, scientists believe they have evidence of liquid water on Mars. It's only a tiny bit, and only in certain seasons, but this salty water makes the hunt for past life on Mars all the more exciting.

We know Mars has water, and we also know that Mars once had liquid water (a whole ocean, in fact) but now it seems we may have evidence of liquid water today. Or during the planet's spring and winter months, anyway. In a study published in Nature Geoscience, researchers report that the Curiosity rover has found signs that thin layers of super-salty water could form and evaporate frequently on the surface of Mars.

The McLaughlin Crater on Mars shows signs it once held a lake. Credit:NASA

The problem with water on Mars is that it doesn't act like water on Earth. The planet's atmospheric pressure is so low that water acts more like dry ice would on Earth: It goes right from solid to gas, skipping the liquid step we're used to seeing in the middle.

But some water on Mars may get so flooded with salt that its freezing temperature lowers significantly.