In 1944, the Dutch-born astronomer Gerald Kuiper was able to tease out the signal of methane from the light reflected back to earth from Saturn’s moon Titan. From there, chemists have theorized about where we might find this methane on this body. Would it be in the air? If so, Kuiper was the first to discover an atmosphere of another moon of our solar system.
Perhaps Titan’s surface was frozen methane. Or perhaps it was in liquid form, something we don’t see on earth. Perhaps this other body in our solar system was like earth in the sense it possessed oceans.
The final determination is not oceans. Most of Titan’s air is nitrogen gas. But the lakes are a fact, according to the press release on the Cassini web site:
The existence of oceans or lakes of liquid methane on Saturn’s moon Titan was predicted more than 20 years ago. But with a dense haze preventing a closer look it has not been possible to confirm their presence. Until the Cassini flyby of July 22, 2006, that is.
Radar imaging data from the flyby, published this week in the journal Nature, provide convincing evidence for large bodies of liquid. This image, used on the journal’s cover, gives a taste of what Cassini saw. Intensity in this colorized image is proportional to how much radar brightness is returned, or more specifically, the logarithm of the radar backscatter cross-section. The colors are not a representation of what the human eye would see.
The lakes, darker than the surrounding terrain, are emphasized here by tinting regions of low backscatter in blue. Radar-brighter regions are shown in tan. The strip of radar imagery is foreshortened to simulate an oblique view of the highest latitude region, seen from a point to its west.
Science fiction writers must adjust their stories to fit the facts now. Oceans were a glamorous possibility. But lakes are cool.
Could Kuiper have imagined 62 years after his discovery of methane that we would find lakes on this cold, orange moon?