Titan is the largest moon of Saturn, and the second-largest satellite in the solar system. Scientists have recently found that it is very similar in structure and has the same natural phenomena as Earth. It is the only other planetary body we have found that has clear evidence of stable bodies of liquid on a solid surface. Lately, researchers have recorded satellite footage that proves there is rainfall on Titan, but it’s not water – it’s methane rain.
All about the rain
According to researchers, it rains only about once every thousand years, but when it does, the water levels can be several inches or even a whopping few feet high in certain regions. These infrequent storms, coupled with wind and ground shifts, create a similar structure to that of Earth, with of course one important difference – the liquid. Unlike the water that is on our planet, Titan’s lakes, rivers, and rain are instead made up of liquid hydrocarbons, like methane, which would make human survival very difficult on the planet-like moon of Titan.
How we found it
In 2004 and 2010 the Cassini spacecraft recorded dark areas of the moon’s surface, associated with cloud activity, which scientists then understood to be rainfall. A significant change near the moon’s equator, about 500,000 square miles, shows that this storm was massive and lasted close to a day. The analysis of this data shows us that the majority of rain showers occur during the polar summer. Even though the storm was massive, the dark spot that was leftover disappeared quickly, suggesting the methane puddle evaporated shortly after the rainfall stopped.
Leading researchers in studying Titan have now proposed a mission to one of its lakes. They want to send the Titan Mare Explorer (TiME) to one of the largest bodies of water on Titan, Ligeia Mare; for 96 days. Scientists want to analyze its depth, chemical composition, and anything else they can find, such as its surrounding environment and weather patterns. TiME will be competing with two other explorers, InSight and Chopper, to go to Titan.
Teams monitoring Titan have not seen any significant cloud activity since 2010 and scientists theorize that it will most probably be a long time before we see rain on Titan again. They believe that this is because Titan has depleted all its methane in the atmosphere and may take several years before there is enough to have a storm again.
Cassini continued to study Saturn, and its rings and moons, until September of 2017. Once it came close to its mission complete date, scientists intentionally piloted the craft into the planet’s atmosphere. The team did this to ensure that no microbes from the craft could potentially come into contact with Titan or its fellow moon Enceladus, both of which could possibly be a suitable environment for new, microscopic life. As the craft descended into Saturn it sent through some final images of the planet’s thick atmosphere.
What we know
Although the planetoid is like Earth in many ways, it is too small for some Earth-like weather phenomena such as cyclones or hurricanes. The average surface temperature is about −179 °C and because the gravity is much weaker than that of Earth’s, and there is a thick haze, raindrops fall a lot slower. Saturn and its many moons also take 29.5 Earth years to complete rotation around the sun, making the observation Titan, and its 7.5 year summers extremely difficult.