Saturn has a lot of moons - and many of them are strange and inhospitable. But this might take the award for the weirdest of the lot.

New Scientist has an interesting report about Methone, a shiny white satellite orbiting within one of Saturn's rings which is literally made of fluff.

Spotted up close for the first time in 2012 by Nasa's Cassini spacecraft, Methone, named after one of the seven daughters of Titan, is a white oval-shaped moon just five kilometres across which orbits in Saturn's E ring, 120,546 miles from the planet.

It is assumed that Methone's strange shape is caused by Saturn's intense gravity, but for a moon to be distorted to that degree it would have to be about three times less dense than water.

Methone is also totally smooth, without any craters or impact scars on its surface - an oddity considering moons that small have no obvious way to fix the damage. They cannot retain an atmosphere, have little gravity and are unable to maintain geological processes - such as volcanoes - that could smooth out the scars.

So why is the moon so smooth, oval and, well, weird?

Apparently, it's made of fluff (or dust).

According to New Scientist, a report made last year at the Lunar and Planetary Science Conference showed that the density of the moon was just 300 kilograms per cubic metre.

In a report at Planetary.org, it is imagined that a well-protected space ship might hypothetically be able to fly right through it.

Despite this knowledge, scientists still aren't sure exactly what Methone is made of, or how it was formed. It's possible that ice on the surface is being levitated by electrons from the planet's radiation belt but that's still an early hypothesis.

Nasa suggests that the moon may have formed after being split from either Mimas or Enceladus, or might have once been part of a larger swarm that orbited close to the planet.

Head over to New Scientist for the full story.

Meanwhile Cassini has moved onto other parts of the Saturn mini-system, and recently produced the first topographic map of its largest moon, Titan.

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  • A crescent Enceladus appears with Saturn's rings in this Cassini spacecraft view of the moon.

  • With giant Saturn hanging in the blackness and sheltering Cassini from the sun's blinding glare, the spacecraft viewed the rings as never before, revealing previously unknown faint rings and even glimpsing its home world.

  • This is an artist's concept of the Saturnian plasma sheet based on data from Cassini magnetospheric imaging instrument. It shows Saturn's embedded 'ring current,' an invisible ring of energetic ions trapped in the planet's magnetic field. Saturn is at the center, with the red 'donut' representing the distribution of dense neutral gas outside Saturn's icy rings. Beyond this region, energetic ions populate the plasma sheet to the dayside magnetopause filling the faintly sketched magnetic flux tubes to higher latitudes and contributing to the ring current. The plasma sheet thins gradually toward the nightside. Image Credit: NASA/JPL/JHUAPL

  • A quartet of Saturn's moons, from tiny to huge, surround and are embedded within the planet's rings in this Cassini composition.

  • This stunning false-color view of Saturn's moon Hyperion reveals crisp details across the strange, tumbling moon's surface. Differences in color could represent differences in the composition of surface materials. The view was obtained during Cassini's very close flyby on Sept. 26, 2005. Hyperion has a notably reddish tint when viewed in natural color. The red color was toned down in this false-color view, and the other hues were enhanced, in order to make more subtle color variations across Hyperion's surface more apparent.

  • The colorful globe of Saturn's largest moon, Titan, passes in front of the planet and its rings in this true color snapshot from NASA's Cassini spacecraft.

  • Vertical structures, among the tallest seen in Saturn's main rings, rise abruptly from the edge of Saturn's B ring to cast long shadows on the ring in this image taken by NASA's Cassini spacecraft two weeks before the planet's August 2009 equinox. Part of the Cassini Division, between the B and the A rings, appears at the top of the image, showing ringlets in the inner division.

  • Flying past Saturn's moon Dione, Cassini captured this view which includes two smaller moons, Epimetheus and Prometheus, near the planet's rings.

  • Data from NASA's Cassini spacecraft show that the sizes and patterns of dunes on Saturn's moon Titan vary as a function of altitude and latitude. Image credit: NASA/JPL-Caltech, and NASA/GSFC/METI/ERSDAC/JAROS and U.S./Japan ASTER Science Team

  • Saturn's small, potato-shaped moon Prometheus appears embedded within the planet's rings near the center of this Cassini spacecraft view while the larger moon Mimas orbits beyond the rings.

  • The line of Saturn's rings disrupts the Cassini spacecraft's view of the moons Tethys and Titan.

  • Although traveling at great speed, the Cassini spacecraft managed to capture this close view of Saturn's small moon Helene during a flyby on March 3, 2010. Saturn's atmosphere makes up the background of this composition.

  • The Cassini spacecraft looks at a brightly illuminated Enceladus and examines the surface of the leading hemisphere of this Saturnian moon.

  • Saturn's third-largest moon Dione can be seen through the haze of its largest moon, Titan, in this view of the two posing before the planet and its rings from NASA's Cassini spacecraft.

  • Saturn's moon Mimas peeks out from behind the night side of the larger moon Dione in this Cassini image captured during the spacecraft's Dec. 12, 2011, flyby of Dione.

  • A quintet of Saturn's moons come together in the Cassini spacecraft's field of view for this portrait.

  • The best view of Saturn's rings in the ultraviolet indicates there is more ice toward the outer part of the rings, than in the inner part, hinting at the origins of the rings and their evolution.

  • NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011.

  • Recent Cassini images of Saturn's moon Enceladus backlit by the sun show the fountain-like sources of the fine spray of material that towers over the south polar region. The image was taken looking more or less broadside at the 'tiger stripe' fractures observed in earlier Enceladus images. It shows discrete plumes of a variety of apparent sizes above the limb of the moon. The greatly enhanced and colorized image shows the enormous extent of the fainter, larger-scale component of the plume.

  • NASA's Cassini spacecraft obtained this unprocessed image on Dec. 12, 2011.

  • Saturn sits nested in its rings of ice as Cassini once again plunges toward the graceful giant. This natural color mosaic was acquired by the Cassini spacecraft as it soared 39 degrees above the unilluminated side of the rings.