NASA’s Cassini spacecraft watched clouds of methane moving across the far northern regions of Saturn’s largest moon, Titan, on 29 and 30 October 2016. Several sets of clouds develop, move over the surface and fade during the course of a movie sequence spanning 11 hours, with one frame taken every 20 minutes. These clouds are measured to move at a speed of about 14 to 22 miles per hour.
A subsurface ocean lies deep within Saturn’s moon Dione, according to new data from the Cassini mission. Two other moons of Saturn, Titan and Enceladus, are already known to hide global oceans beneath their icy crusts. Researchers believe that Dione’s crust floats on an ocean several tens of kilometres deep located 100 kilometres below the surface.
The puzzling appearance of an ice cloud seemingly out of thin air in the stratosphere of Titan has prompted NASA scientists to suggest that a different process than previously thought — possibly similar to one seen over Earth’s poles — could be forming clouds in the giant Saturnian moon’s hazy, brownish-orange atmosphere.
After more than 12 years studying Saturn, its rings and moons, NASA’s Cassini spacecraft has entered the final year of its epic voyage. The Grand Finale will come on 15 September 2017 as Cassini dives into Saturn’s cloud tops, where friction with the atmosphere will cause the spacecraft to burn up like a meteor.
In the bright evening twilight of 14, 15 and 16 July, observers in the British Isles and Western Europe can see the waxing gibbous Moon pass by Mars, first-magnitude star Antares in Scorpius, then Saturn. This series of conjunctions occurs very low in the southern sky for UK-based astronomers, while Australasian observers are ideally placed to view the spectacle almost overhead.
Overall, about 1 kg of material is escaping our atmosphere every second. Every day, around 90 tonnes of material escapes from our planet’s upper atmosphere and streams out into space. Although missions such as ESA’s Cluster fleet have long been investigating this leakage, there are still many open questions. How and why is Earth losing its atmosphere?
The space environment around a planet plays a key role in determining what molecules exist in the atmosphere – and whether the planet is habitable for life. New research shows that Venus has an “electric wind” strong enough to remove the components of water from its upper atmosphere, which may have played a significant role in stripping Earth’s twin planet of its oceans.
On the evening of Monday, 30 May, Mars is closer to Earth than at any time since 30 October 2005. This begs the question: just how close can Mars get? Ade Ashford gives you an overview of close Martian oppositions past, present and future. Also, Friday, 3 June sees the opposition of Saturn, the other planet visible low in the south around midnight.
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