Titan Surface Temperatures from Cassini CIRS 2004-2016
- Dec 12, 2016
- 3 min read
This sequence of maps shows varying surface temperatures on Saturn's moon Titan at two-year intervals, from 2004 to 2016. The measurements were made by the Composite Infrared Spectrometer (CIRS) instrument on NASA's Cassini spacecraft.
The maps show thermal infrared radiation (heat) coming from Titan's surface at a wavelength of 19 microns, a spectral window at which the moon's otherwise opaque atmosphere is mostly transparent. Temperatures have been averaged around the globe from east to west (longitudinally) to emphasize the seasonal variation across latitudes (from north to south). Black regions in the maps are areas for which there was no data.
Titan's surface temperature changes slowly over the course of the Saturn system's long seasons, which each last seven and a half years. As on Earth, the amount of sunlight received at each latitude varies as the sun's illumination moves northward or southward over the course of the 30-year-long Saturnian year.
When Cassini arrived at Saturn in 2004, Titan's southern hemisphere was in late summer and was therefore the warmest region. Shortly after the 2009 equinox, in 2010, temperatures were symmetrical across the northern and southern hemispheres, mimicking the distribution observed by Voyager 1 in 1980 (one Titan year earlier). Temperatures subsequently cooled in the south and rose in the north, as southern winter approached.
While the overall trend in the temperature shift is clearly evident in these maps, there is narrow banding in several places that is an artifact of making the observations through Titan's atmosphere. The moon's dense, hazy envelope adds noise to the difficult measurement.
Image: Titan's atmosphere makes Saturn's largest moon look like a fuzzy orange ball in this natural color view from the Cassini spacecraft. Titan's north polar hood is visible at the top of the image, and a faint blue haze also can be detected above the south pole at the bottom of this view. This view looks toward the anti-Saturn side of Titan (3,200 miles, or 5,150 kilometers across). North is up. Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were obtained with the Cassini spacecraft wide-angle camera on Jan. 30, 2012 at a distance of approximately 119,000 miles (191,000 kilometers) from Titan. Image scale is 7 miles (11 kilometers) per pixel.
The animation above shows a simplified model of the varying temperature data at yearly intervals. The latitude banding has been smoothed to more clearly show the how Titan's peak temperature moves from 19 degrees south to 16 degrees north latitude between 2004 and 2016. The small globe in the upper right corner shows the view of Titan as seen from the direction of the sun. The latitude on Titan where the sun is directly overhead (the subsolar latitude) is indicated by a yellow star.
Although it moves in latitude, the maximum measured temperature on Titan remains around -292 degrees Fahrenheit (-179.6 degrees Celsius, 93.6 Kelvin), with a minimum temperature at the winter pole only 6 degrees Fahrenheit (3.5 degrees Celsius or Kelvin) colder. This is a much smaller contrast than exists between Earth's warmest and coldest temperatures, which can vary by more than 200 degrees Fahrenheit, or more than 100 degrees Celsius.
These Titan surface temperature maps are a visualization of measurements that appeared in publication as: D. E. Jennings et al., Astrophysical Journal Letters, 816, L17, 2016, http://dx.doi.org/10.3847/2041-8205/816/1/L17.
For more information about the Cassini-Huygens mission visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.
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TITAN
Titan is the largest moon of Saturn. It is the only moon known to have a dense atmosphere,[10] and the only object in space other than Earth where clear evidence of stable bodies of surface liquid has been found.
Titan is the sixth ellipsoidal moon from Saturn. Frequently described as a planet-like moon, Titan's diameter is 50% larger than Earth's natural satellite, the Moon, and it is 80% more massive. It is the second-largest moon in the Solar System, after Jupiter's moon Ganymede, and is larger than the smallest planet, Mercury, although only 40% as massive.
Discovered in 1655 by the Dutch astronomer Christiaan Huygens, Titan was the first known moon of Saturn, and the sixth known planetary satellite. Titan orbits Saturn at 20 Saturn radii. From Titan's surface Saturn subtends an arc of 5.7 degrees and would appear 11.4 times the size our moon does to us.
Titan (moon) https://en.wikipedia.org/wiki/Titan_(moon)
Image Credit: NASA/JPL-Caltech/GSFC
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