by Playfuls Staff |
27th July 2006
The
Cassini spacecraft, using its radar system, has discovered very strong evidence
for hydrocarbon lakes on Titan. Dark patches, which resemble terrestrial lakes,
seem to be sprinkled all over the high latitudes surrounding Titan's north
pole. [more]
Scientists
have speculated that liquid methane or ethane might form lakes on Titan,
particularly near the somewhat colder polar regions. In the images, a variety
of dark patches, some with channels leading in or out of them, appear. The
channels have a shape that strongly implies they were carved by liquid. Some of
the dark patches and connecting channels are completely black, that is, they
reflect back essentially no radar signal, and hence must be extremely smooth.
In some
cases rims can be seen around the dark patches, suggesting deposits that might
form as liquid evaporates. The abundant methane in Titan's atmosphere is stable
as a liquid under Titan conditions, as is its abundant chemical product,
ethane, but liquid water is not. For all these reasons, scientists interpret
the dark areas as lakes of liquid methane or ethane, making Titan the only body
in the solar system besides Earth known to possess lakes. Because such lakes
may wax and wane over time, and winds may alter the roughness of their
surfaces. Repeat coverage of these areas should test whether indeed these are
bodies of liquid.
These
two radar images were acquired by the Cassini radar instrument in synthetic
aperture mode on July 21, 2006. The top image centered near 80 degrees north,
92 degrees west measures about 420 kilometers by 150 kilometers (260 miles by
93 miles). The lower image centered near 78 degrees north, 18 degrees west
measures about 475 kilometers by 150 kilometers (295 miles by 93 miles).
Smallest details in this image are about 500 meters (1,640 feet) across.
