Titan, Saturn’s largest moon, has been known to be the only astronomical object in the solar system other than the earth found to possess a great amount of liquid on its surface, but it is not until recently that fog has been found on Titan.
Scientists from the California Institute of Technology (Caltech) and University of California, Berkeley, headed by Dr. Mike Brown, analyzed data from the Cassini spacecraft’s Visual and Infrared Mapping Spectrometer (VIMS), which has been conducting “hyperspectral” imaging on Titan, covering a large area of both the visible and infrared spectrum.
They discovered that Titan’s south pole has numerous puddles of liquid methane, giving rise to sporadic layers of fog.
The presence of fog is an evidence for a hydrological cycle, which was previously known to only exist on Earth.
“Fog—or clouds, or dew, or condensation in general—can form whenever air reaches about 100 percent humidity,” said Brown in a press release. “There are two ways to get there. The first is obvious: add water (on Earth) or methane (on Titan) to the surrounding air. The second is much more common: make the air colder so it can hold less water (or liquid methane), and all of that excess needs to condense.”
It is impossible for the latter to happen on Titan because it takes a long time to change the temperature of Titan’s atmosphere. “If you were to turn the sun totally off, Titan’s atmosphere would still take something like 100 years to cool down,” Brown explained. “Even the coldest parts of the surface are much too warm to ever cause fog to condense.”
“A Titanian mountain would have to be about 15,000 feet high before the air would get cold enough to condense,” he said, but since its crust is icy and fragile, it could not carry any mountain higher than 3000 feet.
“The presence of fog on Titan proves, for the first time, that the moon has a currently active methane hydrological cycle,” Brown said.
To read the research paper, please visit http://www.gps.caltech.edu/~mbrown/papers/ps/fog_pp.pdf.
Scientists from the California Institute of Technology (Caltech) and University of California, Berkeley, headed by Dr. Mike Brown, analyzed data from the Cassini spacecraft’s Visual and Infrared Mapping Spectrometer (VIMS), which has been conducting “hyperspectral” imaging on Titan, covering a large area of both the visible and infrared spectrum.
They discovered that Titan’s south pole has numerous puddles of liquid methane, giving rise to sporadic layers of fog.
The presence of fog is an evidence for a hydrological cycle, which was previously known to only exist on Earth.
“Fog—or clouds, or dew, or condensation in general—can form whenever air reaches about 100 percent humidity,” said Brown in a press release. “There are two ways to get there. The first is obvious: add water (on Earth) or methane (on Titan) to the surrounding air. The second is much more common: make the air colder so it can hold less water (or liquid methane), and all of that excess needs to condense.”
It is impossible for the latter to happen on Titan because it takes a long time to change the temperature of Titan’s atmosphere. “If you were to turn the sun totally off, Titan’s atmosphere would still take something like 100 years to cool down,” Brown explained. “Even the coldest parts of the surface are much too warm to ever cause fog to condense.”
“A Titanian mountain would have to be about 15,000 feet high before the air would get cold enough to condense,” he said, but since its crust is icy and fragile, it could not carry any mountain higher than 3000 feet.
“The presence of fog on Titan proves, for the first time, that the moon has a currently active methane hydrological cycle,” Brown said.
To read the research paper, please visit http://www.gps.caltech.edu/~mbrown/papers/ps/fog_pp.pdf.
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