Proceedings of the National Academy of Sciences on April 24, help confirm expert predictions of what Mars is like at its center. Planetary scientists believe that it turned into the barren world it is today for two reasons: first, that the planet periodically veered in its tilt compared to the sun, meaning that the seasons would be unpredictable or one side of the planet might never see light. This increases the likelihood that life may have once existed on our neighboring planet, but if so, we still haven't found direct evidence of this