Modern-day Mars experiences cyclical changes in climate and, consequently, ice distribution. Unlike Earth, the obliquity (or tilt) of Mars changes substantially on timescales of hundreds of thousands to millions of years. At present day obliquity of about 25-degree tilt on Mars' rotational axis, ice is present in relatively modest quantities at the north and south poles (top left). This schematic shows that ice builds up near the equator at high obliquities (top right) and the poles grow larger at very low obliquities (bottom) (References: Laskar et al., 2002; Head et al., 2003). Credit:...

Jezero Crater as Seen by ESA's Mars Express Orbiter: This image shows the remains of an ancient delta in Mars' Jezero Crater, which NASA's Perseverance Mars rover will explore for signs of fossilized microbial life. Credit: NASA The remnants of ancient dunes aren’t...

This false-color image shows Titan’s second-largest body of liquid, Ligeia Mare, in the moon’s northern hemisphere. Scientists think that rivers flowing into large bodies of liquids like this one should form deltas. Credit: NASA/JPL-Caltech/ASI/Cornell New research...

Apollo 15 lunar module with Mons Hadley in the background. Credit: NASA / JSC / ASU / Andy Saunders I don’t know about you, but there have been a lot of random times when I or someone near me has said, “Someday archaeologists are going to have a field day with…” as we...