Vid Flumina is a river of liquid

methane Methane ( , ) is a chemical compound with the chemical formula (one carbon atom bonded to four hydrogen atoms). It is a group-14 hydride, the simplest alkane, and the main constituent of natural gas. The relative abundance of methane on Eart ...

and

ethane Ethane ( , ) is an organic chemical compound with chemical formula . At standard temperature and pressure, ethane is a colorless, odorless gas. Like many hydrocarbons, ethane is isolated on an industrial scale from natural gas and as a petr ...

Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...

's moon Titan. The river has been compared to the

Nile The Nile, , Bohairic , lg, Kiira , Nobiin language, Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered ...

. It is more than long and flows into Titan's second largest hydrocarbon sea,

Ligeia Mare Ligeia Mare is a lake in the north polar region of Titan, the planet Saturn's largest moon. It is the second largest body of liquid on the surface of Titan, after Kraken Mare. Larger than Lake Superior on Earth, it is mostly composed of liqui ...

. The surface of Titan is mostly water ice, so Vid Flumina is a river of methane and ethane flowing across and cutting canyons into ice as though it were bedrock. NASA scientists think that it likely has rapids, whirlpools and waterfalls, just like rivers on Earth.

Discovery

Earlier findings

In 2004,

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

's probe, ''Cassini'' arrived at Saturn to study it and its moons. The scientists at NASA were expecting to find some evidence for liquid methane because of Titan's surface temperature and its methane-rich atmosphere. However, ''Cassini'' early findings that were focused on Titan's equator revealed no traces of seas or rivers. The early disappointment changed as the ''Cassini'' orbit shifted and allowed the researchers at NASA to bounce radar off other regions of the moon. The radar signals were then routinely reflected off angled, rough features such as sand dunes and rocks and cliffs, but when the radar reached the polar regions of Titan, the regular signals ceased. These non-reflecting dark spots were actually reminiscent of the lakes, rivers and tributaries on Earth.

Discovery

In December 2012, Jani Radebaugh, a scientist on ''Cassini'' team along with an international team of colleagues, announced that they had discovered a liquid methane river of over 200 miles resembling the Nile from an image taken on 26 September 2012.

Geology

The river flows along a relatively straight course, suggesting that it follows one or more

fault line In geology, a fault is a planar fracture or discontinuity in a volume of rock across which there has been significant displacement as a result of rock-mass movements. Large faults within Earth's crust result from the action of plate tectonic ...

s, similar to other large nearby rivers. The river slices through a rough and slanted terrain, which suggests operation of processes similar to tectonic movements on Earth. Radar studies show that Vid Flumina and its tributaries flow through canyons about one km wide and 0.57 km deep, with slopes of about 40°. Flowing methane was detected in the channels. The elevation of the main channel was found to be within 1 m of that of

, while tributary channels have higher elevations. The canyons are thought to have formed by erosion stimulated either by uplift of the area or a decline in the level of Ligeia Mare.

References

{{Titan Rivers Surface features of Titan (moon)