Credit NASA:
This is a sunlight reflection (a specular reflection) from Saturn’s Moon Titan. It was detected by the visual and infrared mapping spectrometer (VIMS) on NASA’s Cassini spacecraft on July 8, 2009. It confirmed the presence of liquid in the moon’s northern hemisphere. That’s pretty rare! Titan is likely the only other moon/planet with a liquid on the surface in similar fashion to Earth. Titan’s “water” is liquid methane, CH4, better known on Earth as natural gas. Regular Earth-water, H2O, would be frozen solid on Titan where the surface temperature is 290o F below zero. Methane, on the other hand, is a flowing liquid.
“This one image communicates so much about Titan — a thick atmosphere, surface lakes and an otherworldliness,” says Bob Pappalardo, Cassini project scientist, based at NASA’s Jet Propulsion Laboratory. “It’s an unsettling combination of strangeness yet similarity to Earth. This picture is one of Cassini’s iconic images.”
The northern hemisphere was shrouded in darkness for nearly 15 years, but that changed as it approached its spring equinox in August 2009. VIMS was able to detect the glint as conditions changed. Titan’s hazy atmosphere also scatters and absorbs many wavelengths of light, including most of the visible light spectrum so this image is created using wavelenghts of light in the 5 micron range.
By comparing the new image to radar and near-infrared light images acquired from 2006 to 2008, Cassini scientists were able to identify the source of the reflection as being the southern shoreline of a Titan lake called Kraken Mare. The reflection appeared to come from a part of the lake around 71 degrees north latitude and 337 degrees west latitude.
According to NASA “It was taken on Cassini’s 59th flyby of Titan on July 8, 2009, at a distance of about 200,000 kilometers (120,000 miles). The image resolution was about 100 kilometers (60 miles) per pixel. Image processing was done at the German Aerospace Center in Berlin and the University of Arizona in Tucson”