Today in space: Saturn’s moons and stellar dancers

15 Aug 2016

NASA’s numerous missions continually provide us with outstanding images from beyond our terrestrial vantage point. Today is no different.

Cassini’s trip to Saturn, one of the more ambitious projects and one which Brian Cox rates as the most successful ongoing mission, is one of the more regular providers of incredible imagery.

NASA Kepler Cassini Saturn

Perhaps behind just Hubble in that regard, Cassini’s original task was a four-year mission ending back in 2008. Since then, a series of extensions, each relating to further documenting of Saturn, will soon culminate in a pole dance.

Starting later this year, the spacecraft will repeatedly climb high above Saturn’s poles, flying just outside its narrowest ring 20 times, then inside it 22 more times.

Brothers in arms

Saturn’s moons Tethys and Hyperion. Image via NASA/JPL-Caltech/Space Science Institute

Saturn’s moons Tethys and Hyperion. Image via NASA/JPL-Caltech/Space Science Institute

As it approaches this stage of its mission, we remember last year, when it provided us with yet another brilliant picture of Saturn’s moons Tethys and Hyperion.

Though in this image they appear to be near neighbours, they are actually 1.5m kilometers apart here. Tethys is the larger body on the left.

Water, water everywhere

More recently, Cassini has found deep, steep-sided canyons on Saturn’s moon Titan that are flooded with “liquid hydrocarbons”, representing the first direct evidence of the presence of liquid-filled channels on Titan.

These canyons are hundreds of metres deep and their dark imagery is like Titan’s predicted methane-rich seas.

NASA Cassini

The circles are where NASA scientists believe liquid rests. Image via NASA/JPL-Caltech/ASI

Christened Rhea

A week or so back, Cassini sent back this comprehensive image of Rhea, one of Saturn’s other bodies, the second-largest after Titan.

Its ancient surface is one of the most heavily cratered of all of Saturn’s moons. “Subtle albedo variations across the disk of Rhea hint at past geologic activity,” said NASA.

Saturn’s moon Rhea. Image via NASA/JPL-Caltech/Space Science Institute

Saturn’s moon Rhea. Image via NASA/JPL-Caltech/Space Science Institute

Spinning stars

Meanwhile, Kepler, another of NASA’s eye-catching missions, recently snapped these stars of the Pleiades cluster, a series of “dancing”, spinning stars.

Studying these particular stars, Kepler’s K2 mission has helped amass the most complete catalogue of rotation periods for stars in a cluster.

Having reached stellar “young adulthood”, these stars are spinning at the fastest they ever will.

The emissions the star produces gradually slows down the rotation, though these stars are nowhere near that stage just yet.

This image shows the Pleiades cluster of stars as seen through NASA’s wide-field infrared survey explorer. Image via NASA/JPL-Caltech/UCLA

This image shows the Pleiades cluster of stars as seen through NASA’s wide-field infrared survey explorer. Image via NASA/JPL-Caltech/UCLA

“We hope that, by comparing our results to other star clusters, we will learn more about the relationship between a star’s mass, its age, and even the history of its solar system,” said Luisa Rebull, a research scientist who worked on this particular project.

“In the ‘ballet’ of the Pleiades, we see that slow rotators tend to be more massive, whereas the fastest rotators tend to be very light stars,” said Rebull.

Gordon Hunt was a journalist with Silicon Republic

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