Rainfall and seasonal weather in Saturn’s moon Titan

Cassini discovered numerous lakes and seas of liquid hydrocarbons on Titan's frigid surface during the probe's pioneering 13 years


The newly-released global image of Titan, the largest moon of Saturn, found evidence of rainfall in the north pole of the satelite.

The Cassini mission to Saturn ended in September 2017, but the data it gathered during its 13-year mission is still yielding scientific results.
The conclusions of the research were gleaned from measurements collected during the final, ultra-close orbits Cassini performed in 2017 as the spacecraft neared the end of its mission. The findings were published online on Thursday in Science.  

Scientists watching Titan have finally gotten evidence that the planet experiences seasons like Earth. The rainfall would be the first indication of the start of a summer season in Titan’s northern hemisphere, according to the study published in the journal Geophysical Research Letters.

Cassini discovered numerous lakes and seas of liquid hydrocarbons on Titan’s frigid surface during the probe’s pioneering 13 years in the Saturn system.

The researchers identified a reflective feature near Titan’s north pole on an image taken on June 7, 2016, by Cassini’s near-infrared instrument, the Visual and Infrared Mapping Spectrometer.

The reflective feature covered about 46,332 square miles and did not appear on images from previous and subsequent Cassini passes.

Analyses of the short-term reflective feature suggested it likely resulted from sunlight reflecting off a wet surface. The study attributes the reflection to a methane rainfall event, followed by a probable period of evaporation.

This reflective surface represents the first observations of summer rainfall on the moon’s northern hemisphere.

If compared to Earth’s yearly cycle of four seasons, a season on Titan lasts seven Earth years.

Cassini studied Saturn, its rings and many moons until September 2017, when the low-on-fuel spacecraft plunged intentionally into the planet’s thick atmosphere. Mission team members ordered the death dive to ensure that Cassini never contaminated Titan and fellow moon Enceladus with microbes from Earth. Scientists think both of these satellites may be capable of supporting life as we know it.

Cassini captured the rainfall-glint image with its Visual and Infrared Mapping Spectrometer instrument, which was able to peer through Titan’s thick, obscuring atmospheric haze.

The Cassini orbiter traveled with a European lander called Huygens, which touched down on Titan in January 2005, pulling off the first-ever soft landing on a moon in the outer system.