T16 RADAR SAR Swath, Land o' lakes |
T16 RADAR SAR Swath, Land o' lakes |
Jul 24 2006, 09:33 PM
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Senior Member Group: Moderator Posts: 3234 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
Much to my surprise, a chunk of the T16 Sar swath as been released:
http://photojournal.jpl.nasa.gov/catalog/PIA08630 An abundance of lakes can been seen. Some appear to be crater lakes (or sinkholes), like the lake at far left on the top cutout. That lake appears similar to Crater Lake in Oregon, with a little island in the middle (you can kinda see the attenuation of the signal surrounding the island as the methane gets deeper). Some lakes appear quite distinctive from the surrounding terrain, like the features on the right part of the bottom cutout. -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Aug 9 2006, 01:02 PM
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Senior Member Group: Members Posts: 2998 Joined: 30-October 04 Member No.: 105 |
I wonder how long twilight lasts on Titan? On Earth, astronimical twilight lasts for about 1.5 hours, or 22 degrees longitude. On Titan, I might expect twilight to last longer since the atmosphere is thicker and deeper (relative to the radius), but it may be "dimmer" since the atmosphere is more opaque.
--Bill -------------------- |
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Aug 9 2006, 03:10 PM
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
I wonder how long twilight lasts on Titan? On Earth, astronimical twilight lasts for about 1.5 hours, or 22 degrees longitude. On Titan, I might expect twilight to last longer since the atmosphere is thicker and deeper (relative to the radius), but it may be "dimmer" since the atmosphere is more opaque. --Bill I'm surprised to see the progression/extent of twilight talked about as a singular thing. It surely varies with season, latitude, and sky conditions. At equinox on the equator, the Sun plunges perpendicularly to the horizon, dropping 15 degree per hour. At midlatitudes, it typically slices at a 45ish-degree angle, and so proceeds below the horizon at about 70% that rate. US/Europe travelers to the tropics may be shocked at how quickly sunset leads to darkness. Of course, in the polar long seasons, even when the Sun does set, it doesn't get very far below the horizon. Even in "clear" weather, humidity and dust can soften/mute the light/dark distinction: humid air 15 km overhead can still "see" the Sun about 20 minutes after sunset, while the air over the western horizon roughly doubles that. But subtract the humidity and the effect becomes much less relevant. In a nutshell, I think the residents of Oslo and Tuscon have a very different experience at twilight. |
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