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The case of the missing Ceres craters

27 July 2016 Astronomy Now

Ceres is covered in countless small, young craters, but none are larger than 175 miles (280 kilometres) in diameter. To scientists, this is a huge mystery, given that the dwarf planet must have been hit by numerous large asteroids during its 4.5 billion-year lifetime. Where did all the large craters go?

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Hubble catches views of a jet rotating with Comet 252P/LINEAR

13 May 2016 Astronomy Now

A sequence of images taken by the NASA/ESA Hubble Space Telescope shows rotation of Comet 252P/LINEAR on 4 April 2016, roughly two weeks after the icy visitor came within 3.3 million miles of Earth, or about 14 times the distance between our planet and the Moon. These observations also represent the closest celestial object Hubble has observed, other than the Moon.

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Evidence builds for ancient under-ice volcanoes on Mars

4 May 2016 Astronomy Now

Volcanoes erupted beneath an ice sheet on Mars billions of years ago, far from any ice sheet on the Red Planet today, new evidence from NASA’s Mars Reconnaissance Orbiter suggests. The research about these volcanoes helps show there was extensive ice on ancient Mars. Such an environment combining heat and moisture could have provided favourable conditions for microbial life.

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Europa’s flexing icy crust might make more heat than scientists thought

15 April 2016 Astronomy Now

As it orbits Jupiter, the icy surface of Europa heaves and falls with the changing pull of its parent planet’s gravity, creating enough heat to likely support a global ocean beneath the Jovian moon’s solid shell. Experiments by geoscientists suggest that this process, called tidal dissipation, could create far more heat in Europa’s ice than scientists had previously assumed.

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One of Saturn’s rings is not like the others

5 September 2015 Astronomy Now

NASA’s Cassini mission scientists were watching closely when the Sun set on Saturn’s rings in August 2009. It was the equinox — one of two times in the Saturnian year when the Sun illuminates the planet’s enormous ring system edge-on — providing an extraordinary opportunity for the spacecraft to observe short-lived changes that reveal details about the nature of the rings.

NASA's reworked image of Europa based on late 1990s data from the Galileo spacecraft.
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Science instruments selected for NASA’s Europa mission

27 May 2015 Astronomy Now

NASA has selected nine science instruments for a future mission to Jupiter’s moon Europa in which a spacecraft would make multiple close flybys of the icy world — thought to contain a global subsurface ocean — to investigate whether the mysterious moon could harbour conditions suitable for life.

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Ceres’ mysterious white spots resolved in latest Dawn images

11 May 2015 Astronomy Now

The enigmatic white features on the dwarf planet Ceres are better resolved in a new sequence of images taken by NASA’s Dawn spacecraft on May 3rd and 4th. In this closest-yet view, the brightest spots within a crater in the northern hemisphere are revealed to be composed of many smaller spots. However, their exact nature remains unknown.