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Saturn spacecraft not affected by gravity of hypothetical Planet 9

9 April 2016 Astronomy Now

Several recent news stories have reported that a mysterious anomaly in the orbit of NASA’s Cassini spacecraft around Saturn could potentially be explained by the gravitational tug of theorised Planet 9, existing far beyond the orbit of Neptune in our solar system. However, NASA cannot find any unexplained deviations in the spacecraft’s orbit.

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The Saturnian sisters

10 March 2016 Astronomy Now

Similar in many ways, Saturn’s moons Tethys and Rhea (left and right, respectively) even share a discoverer: Giovanni Cassini, namesake of the NASA spacecraft that captured this view. Although somewhat different in size, Rhea (949 miles across) and Tethys (660 miles) are both composed largely of ices and are generally thought to be geologically inactive today.

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Researchers home in on likely whereabouts of Planet Nine

27 February 2016 Astronomy Now

Using observations from NASA’s Cassini spacecraft, a team of French astronomers from the Institut de mécanique céleste et de calcul des éphémérides, and the laboratory GeoAzur have been able to specify the possible positions of a ninth planet in the Solar System.

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A trio of Saturnian moons

23 February 2016 Astronomy Now

Three of Saturn’s moons — Tethys, Enceladus and Mimas — are captured in this group photo from NASA’s Cassini spacecraft. Tethys appears above the rings, while Enceladus sits just below centre and Mimas hangs below and to the left of Enceladus. This view looks toward the sunlit side of the rings from narrowly above the ring plane.

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Taking Titan’s temperature 2004-2016

23 February 2016 Astronomy Now

Based on measurements made by the Composite Infrared Spectrometer (CIRS) instrument on NASA’s Cassini spacecraft, scientists have produced a sequence of maps showing the varying surface temperatures on Saturn’s moon Titan at two-year intervals, from 2004 to 2016.

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Saturn’s moon Prometheus seen up close

9 December 2015 Astronomy Now

NASA’s Cassini spacecraft spied details on the pockmarked surface of Saturn’s moon Prometheus (86 kilometres, or 53 miles across) during a moderately close flyby on 6 December 2015. This is one of Cassini’s highest resolution views of Prometheus, a moon which orbits Saturn just interior to the narrow F ring, which is seen here at top.

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A brighter Saturnian moon

18 November 2015 Astronomy Now

Although Saturn’s moons Dione (near) and Enceladus (far) are composed of nearly the same materials, Enceladus has a considerably higher reflectivity than Dione. As a result, it appears brighter against the dark night sky. This image was taken by NASA’s Cassini spacecraft in visible light with the narrow-angle camera on 8 September 2015.

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Closest northern views of Enceladus, Saturn’s cracked moon

16 October 2015 Astronomy Now

NASA’s Cassini spacecraft has begun returning its best-ever views of the northern extremes of Saturn’s icy, ocean-bearing moon Enceladus. Scientists expected the north polar region of Enceladus to be heavily cratered, based on low-resolution images from the Voyager mission, but the new high-resolution Cassini images show a landscape of stark contrasts.

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Asteroids found to be the Moon’s main ‘water supply’

3 October 2015 Astronomy Now

Water reserves found on the Moon are the result of asteroids acting as “delivery vehicles” and not of falling comets as was previously thought. Using computer simulation, scientists from the Moscow Institute of Physics and Technology and the RAS Geosphere Dynamics Institute have discovered that a large asteroid can deliver more water to the lunar surface than the cumulative fall of comets over a billion year period.