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Locally enhanced precipitation organized by planetary-scale waves on Titan
Turtle, Elizabeth P.; Mitchell, Jonathan L.; Ádámkovics, Máté +1 more
Saturn's moon Titan exhibits an active weather cycle that involves methane. Equatorial and mid-latitude clouds can be organized into fascinating morphologies on scales exceeding 1,000km (ref. ). Observations include an arrow-shaped equatorial cloud that produced detectable surface accumulation, probably from the precipitation of liquid methane. An…
Equatorial winds on Saturn and the stratospheric oscillation
Fletcher, Leigh N.; West, Robert A.; Porco, Carolyn C. +13 more
The zonal jets on the giant planets have been thought to be stable in time. A decline in the velocity of Saturn's equatorial jet has been identified, on the basis of a comparison of cloud-tracking data across two decades, but the differences in cloud speeds have since been suggested to stem from changes in cloud altitude in combination with vertic…
Ancient ocean on Mars supported by global distribution of deltas and valleys
Hynek, Brian M.; di Achille, Gaetano
The climate of early Mars could have supported a complex hydrological system and possibly a northern hemispheric ocean covering up to one-third of the planet's surface. This notion has been repeatedly proposed and challenged over the past two decades, and remains one of the largest uncertainties in Mars research. Here, we used global databases of …
The role of episodic overturn in generating the surface geology and heat flow on Enceladus
Nimmo, Francis; O'Neill, Craig
The Saturnian satellite Enceladus is enigmatic in that its geologically active south polar region shows high heat flows and geysers not seen elsewhere on the satellite at present; its heavily deformed surface shows an episodic age distribution; and the current observed heat loss exceeds the long-term tidal equilibrium heat production by a factor o…
Photolysis of sulphuric acid as the source of sulphur oxides in the mesosphere of Venus
Montmessin, Franck; Bertaux, Jean-Loup; Zhang, Xi +3 more
The sulphur cycle plays fundamental roles in the chemistry and climate of Venus. Thermodynamic equilibrium chemistry at the surface of Venus favours the production of carbonyl sulphide and to a lesser extent sulphur dioxide. These gases are transported to the middle atmosphere by the Hadley circulation cell. Above the cloud top, a sulphur oxidatio…
Planetary science: Tectonic overturn on Enceladus
Helfenstein, Paul
The south pole of Saturn's icy moon Enceladus is anomalously warm, geologically youthful and cryovolcanically active. Episodic convective overturn explains how the moon's modest sources of internal heat can be channelled into intense geological activity.
Multiple origins of linear dunes on Earth and Titan
Rubin, David M.; Hesp, Patrick A.
An asymmetric distribution of lakes on Titan as a possible consequence of orbital forcing
Lorenz, R. D.; Lunine, J. I.; Hayes, A. G. +3 more
A set of lakes filled or partially filled with liquid hydrocarbon and empty lake basins have been discovered in the high latitudes of Saturn's moon Titan. These features were mapped by the radar instrument on the Cassini orbiter. Here we quantify the distribution of the lakes and basins, and show a pronounced hemispheric asymmetry in their occurre…
Multiple origins of linear dunes on Earth and Titan
Rubin, David M.; Hesp, Patrick A.
Dunes with relatively long and parallel crests are classified as linear dunes. On Earth, they form in at least two environmental settings: where winds of bimodal direction blow across loose sand, and also where single-direction winds blow over sediment that is locally stabilized, be it through vegetation, sediment cohesion or topographic shelter f…
Earth's ionospheric outflow dominated by hidden cold plasma
André, M.; Eriksson, A. I.; Cully, C. M. +3 more
The Earth constantly loses matter, mostly in the form of H+ and O+ ions. Analysis of measurements from the Cluster spacecraft reveals that the total loss of cold ions, below 1 eV in thermal energy, is larger than the previously observed, more energetic, outflow.