Topic: Solar Systems
(Big-)Moonless worlds have unstable tilts

(Big-)Moonless worlds have unstable tilts

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:...

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Perseverance collects a River of Science

Perseverance collects a River of Science

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...

How Rivers Flow: Here, Mars & Titan

How Rivers Flow: Here, Mars & Titan

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...