Sunday, June 2, 2013

All About Saturn's moon -- Titan

For today's posting I had originally intended on posting some of NASA's latest images.  The first image I checked out (see below) is a photo of one of the largest bodies of liquid found in the solar system outside the Earth.  The lake shown in the photo below, Ontario Lacus – named after North America’s Lake Ontario – is the largest lake in Titan’s southern hemisphere’s.  Scientists who have studied images report that its shoreline receded by about six miles from June 2005 to July 2009 as a result of evaporation during the southern hemisphere's "summer" season.  A year on Titan lasts 29.5 Earth years so summer is a long time coming.

The image below shows how big Titan's lake is to Lake Superior.
 The weather is now shifting on this giant moon.  Titan's north polar region, which is covered with sprawling hydrocarbon seas and lakes, was dark when Cassini first arrived at the Saturn system in 2004. But sunlight has been creeping up Titan's northern hemisphere since August 2009, when the sun's light crossed the equatorial plane at equinox. Titan's seasons take about seven Earth years to change. By 2017, the end of Cassini's mission, Titan will be approaching northern solstice, the height of summer. Given the wind-sculpted dunes Cassini has seen on Titan, scientists are expecting to see wind-driven waves on the northern lakes once the sun-driven weather systems impact the moon's northern region.

Titan (or Saturn VI) is the largest moon of Saturn.  It is the only moon in our solar system known to have a dense atmosphere, and the only object other than Earth that has visible liquid on its surface.
Titan is the sixth moon from Saturn. Frequently described as a planet-like moon, Titan has a diameter roughly 50% larger than the Moon and is 80% more massive. It is the second-largest moon in the Solar System, after Jupiter's moon Ganymede, and is larger by volume than the smallest planet, Mercury, although only about 41% as massive.  Titan is 3,200 miles  across (5,150 km), compared to 3,031 miles for the planet Mercury (4,879 km) , and 2,159 miles for the Moon (3,474 km) , and 12,742 km for the Earth.

In the photo below Titan is on the lower left; the moon is in the upper left.

Titan was the first known moon of Saturn, discovered in 1655 by the Dutch astronomer Christiaan Huygens, and was the fifth moon of a planet apart from the Earth to be discovered.

Titan is likely differentiated into several layers with a 2,113 mile wide rocky center (3,400 km) surrounded by several layers composed of different crystal forms of ice. Its interior may still be hot and there may be a liquid layer consisting of a "magma" composed of water and ammonia between the different layers of ice. The presence of ammonia allows water to remain liquid even at temperatures as low as 176 K.

Titan is primarily composed of water ice and rocky material. Much as with Venus prior to the Space Age, the dense, opaque atmosphere prevented understanding of Titan's surface until new information accumulated with the arrival of the Cassini–Huygens mission in 2004, including the discovery of liquid hydrocarbon lakes in the satellite's polar regions. The surface is geologically young; although mountains and several possible cryovolcanoes have been discovered, it is smooth and few impact craters have been found.

The atmosphere of Titan is largely composed of nitrogen; minor components lead to the formation of methane and ethane clouds and nitrogen-rich organic smog. The climate—including wind and rain—creates surface features similar to those of Earth, such as dunes, rivers, lakes and seas (probably of liquid methane and ethane), and deltas, and is dominated by seasonal weather patterns as on Earth. With its liquids (both surface and subsurface) and robust nitrogen atmosphere, Titan's methane cycle is viewed as being similar to Earth's water cycle, although at a much lower temperature

The natural color composite above was taken during the Cassini spacecraft's April 16, 2005, flyby of Titan. It is a combination of images taken through three filters that are sensitive to red, green and violet light. It shows approximately what Titan would look like to the human eye: a hazy orange globe surrounded by a tenuous, bluish haze. The orange color is due to the hydrocarbon particles which make up Titan's atmospheric haze.  North on Titan is up and tilted 30 degrees to the right.

A black and white image of Titan is below.

The photo below shows the small, battered moon Epimetheus and the large smog-enshrouded Titan, with Saturn's A and F rings stretching across the scene.  Epimetheus is 116 kilometers (72 miles) across and giant Titan is 5,150 kilometers (3,200 miles) across.
If you were to visit the moon, Titan, you would be able to fly on the surface with a pair of homemade wings.  This is possible due toTitan’s thick atmosphere, low gravity (less than our Moon) and available surface pressure (although it is 50% of Earth’s).  So if you jumped up and flapped a pair of wings strapped to your arms, you could fly with no more effort than walking.
The photo above shows what it may look like if you were in a boat on Titan's moon looking up in the sky at Saturn.


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