The Cassini Spacecraft has captured an image of the hydrocarbon seas of Titan with sunlight glinting off them.
Cassini has previously taken images of the Titan's seas through breaks in the clouds.
University of Arizona. Kraken Mare, the largest sea on Titan is at the upper right.
It has also produced images where a beam of sunlight was picked up reflecting off a lake, in this case Kivu Lacus.
University of Arizona. The white is reflection. The pink is skyglow, haze illuminated by the reflected light.
However, the latest image is the first to combine the two. With three small exceptions, Titan's lakes and seas sit in the northern polar region, and through the hemisphere's long winter the sun never reached them. “Specular reflections can only be seen when the Cassini spacecraft is in the right place relative to the sun and Titan such that the mirror-like reflection from a lake reflects sunlight directly to the spacecraft," NASA pointed out when the first reflection images were released. "They require the sun to be above the horizon at the location of the lake, which is why none were visible until after Titan's northern spring equinox in 2009 when the seas became illuminated,”
The image at the top of the page represents the first time the two have been captured together. It is a mosaic taken in the near-infrared with the wavelengths shifted into the visible spectrum. The bright patch is the southern part of Kraken Mare, a basin of methan and ethane the size of the Caspian Sea and Lake Superior combined. Nevertheless, the bright evaporative deposits around the Mare suggest it was once substantially larger.
The image was possible because with Titan's well into its northern summer the sun has reached 40 above the horizon at the Mare's southern latitudes, allowing a stronger reflection than when it was only just reaching the lake.
To the right of the Kraken Mare is a network of channels that connect it to Ligeia Sea. This image allows astronomers to see the area to unprecedented detail. The clouds visible above Ligeia are, NASA says, “made of liquid methane droplets, and could be actively refilling the lakes with rainfall.”
