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Published on February 10th, 2012 | by Yellow Magpie

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Uranus’s Moon Oberon: A Cold Unknown World

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Uranus’s Moon Oberon

It is a world that remains only partly seen. A flying-probe took a few images as it shoots past the far-away satellite. From these paltry pictures we have garnered much of our present picture of the Uranus’s moon Oberon.

Uranus’s moon Oberon is the second largest moon of Uranus. Like many of the other satellites orbiting Uranus, Oberon is named after characters from Shakespeare’s A Midsummer Night’s Dream.

Uranus’s moon Oberon orbits Uranus at a distance of 584,000 kilometres (362,000 miles) taking roughly 13.5 days to complete one trip around the planet. The moon is a very cold world with temperatures as low as minus 203 degrees Celsius (minus 333 degrees Fahrenheit)

 Uranus's Moon Oberon (False Colour Image)

Uranus’s Moon Oberon: Violent Origins

It is thought that the moon was created from an accretion disk that was left over after Uranus’s formation. This field of debris coalesced over thousands of years and formed the satellite. Like the other Uranian moons, Uranus’s Oberon is composed mainly of nearly equal amounts of ice and solid rock.

Scientists believe that the moon has an icy mantle and an inner rocky core. There is considerable speculation as to whether or not there is a layer of liquid water present at the boundary between the core and the mantle.

Heavily Cratered Canyon Surface

From the 25 per cent that Voyager 2 mapped in sufficient detail scientists have noted two types of features on Uranus’s moon Oberon’s surface. These are canyons called chasmata and craters. Oberon’s surface is thought to be the most heavily cratered of all the Uranian satellites. In fact, it is almost saturated with craters which means that a new impact is likely to erase older impacts.

The largest canyon so far discovered on Uranus’s moon Oberon is Momur Chasma. Oberon’s canyons were created quite early in its history and are the result of tectonic activity when the moon expanded.

Uranus’s moon Oberon’s surface is pockmarked with scars from heavy impacts from both comets and asteroids.Unfortunately, only 40 per cent of the entire moon’s surface has been mapped. This was done by Voyager 2 in 1986 as the probe navigated its way past the planets on its long trip out of the Solar System.

However, just 25 per cent of the surface was mapped in sufficient detail as to allow geological mapping. The entire northern hemisphere was shrouded in darkness during Voyager 2’s mapping so its features are completely unknown.

One of the largest craters so far discovered on the moon’s surface is 210 kilometres (130 miles) across.

Painting Of Voyager 2 Which Flew Past Uranus's Moon Oberon

Uranus’s Moon Oberon: A Hostile Orbit

Uranus odd orbital tilt means that the Uranian moons are subject to extreme seasons. Each of the hemispheres of Uranus’s moon Oberon experience complete darkness and complete sunlight for 42 years at a time.

The moon is tidally locked, like our own Moon. This means that one side continuously faces Uranus while the other always points away from the planet’s surface.

Like Titania, a substantial portion of the orbit of Uranus’s moon Oberon’s resides outside the magnetosphere of Uranus. This means that Oberon is bombarded by magnetospheric plasma. Nevertheless, the darkening of the trailing hemisphere, which is typical of the Uranian moon system, is not found on Oberon.

Scientists know this because of the density of the moon. One theory proposed for this departure from the other satellites is that the trailing hemisphere of Uranus’s moon Oberon has more water ice compared to its leading hemisphere. This is completely at odds with all the other Uranian satellites.

One theory proposed to explain this anomaly is impact gardening. Impact gardening is the creation of fine soil through heavy impacts.

A Liquid Ocean?

Uranus’s moon Oberon may have a liquid ocean at the core-mantle boundary. This is heavily reliant on there being enough of an anti-freeze material present to stop the water freezing. If the ocean does exist it could be up to 40 kilometres (25 miles) deep. At this stage, given the dearth of information, it is impossible to say whether this is the case or not.

It may be quite some time before a spacecraft is sent to explore either Uranus or Oberon. As of now there are no planned missions to Uranus’s moon Oberon.

Highly Recommended Reading

Check out Yellow Magpie’s Uranus: The Coldest Ice Giant for more insight into the largest planet in the Solar System.

You may also wish to take a gander at The Solar System And Beyond: A Guide To The Cosmos.
Cosmos is a highly recommended book. It contains large, full-page pictures of the asteroids and writing on the subject by the highly competent author, Giles Sparrow.

Amazon.co.uk

For people living in Ireland or the United Kingdom, you can access: Cosmos from here.

Amazon.ca

For those who live in Canada, you can obtain: Cosmos here.

Amazon.de

For Germany: Cosmos.

Amazon.fr

For France: Cosmos.


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