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Rings and moons are the matter that orbit a celestial body other than a star. Rings are a collection of dust or small particles that form into a flat disk. Moons, or natural satellites, are much larger single bodies. Large moons can themselves support rings.
Icy planets and moons could become habitable as their host stars brighten and their ice melts. Climate simulations instead show a rapid transition from a snowball to an inhospitable greenhouse climate with significant water loss.
Total solar eclipses are a unique opportunity to study the lower solar corona where the solar wind originates. This review presents the recent advancements in coronal science from eclipses and the scientific and outreach plans for this year's totality.
Cassini’s camera observed Titan from orbit at different angles (0–166°) and found that the planet looks brighter towards the night than at midday. This effect, linked to the scattering properties of Titanian haze, can also be present in exoplanets.
Liquid methane lakes dot Titan’s polar regions. Numerical models reveal that the creation of buoyant bubbles through nitrogen exsolution near the bed of the Ligeia Mare lake can explain transient brightenings observed by Cassini on the lake’s surface.
Frictional charging of granular materials may readily occur on Saturn’s moon Titan. Laboratory experiments under Titan-like conditions suggest that the resulting electrostatic forces are strong enough to affect sand transport on Titan.
In our own solar system, Venus is too hot, Mars is too cold and Earth is just right. Simulations show that making an icy planet habitable is not as simple as melting its ice: many icy bodies swing from too cold to too hot, bypassing just right.
The seabed of Ligeia Mare, a hydrocarbon sea at the north pole of Titan, may be a favourable place for the separation of nitrogen and the creation of bubbles that then buoyantly rise to the sea's surface.
The twin isotopic signatures of the Moon and Earth are difficult to explain by a single giant impact. Impact simulations suggest that making the Moon by a combination of multiple, smaller moonlet-forming impacts may work better.
After more than a decade exploring Saturn and its moons, the Cassini mission is in its closing act. Cassini's last year is an encore performance stuffed with science, including a final plunge into Saturn's atmosphere.
The two small satellites of Mars are thought to have accreted from a debris disk formed in a giant impact. Simulations suggest the moons were shepherded into formation by the dynamical influence of one or more short-lived massive inner moons.