Astronomers Found Evidence of a Curious Weather Phenomenon on Titan

Astronomers Found Evidence of a Curious Weather Phenomenon on Titan

Astronomers Found Evidence of a Curious Weather Phenomenon on Titan

Scientists have finally found the first evidence of seasonal storms on Titan.

The Cassini Spacecraft of NASA reached the orbit of Saturn in 2004. At that time, it was summer on the Southern Hemisphere of Titan, the largest moon of the planet. Since then, researchers have been waiting eagerly to watch the signs of seasonal changes on the moon because the climate of Titan is quite similar to what we observe on Earth. For instance, the axial tilt of Titan is around 27 degrees while the tilt of our planet is about 23.5 degrees. Similarly, it is tidally locked to Saturn, which means that the length of a day (15.9 Earth days) on the moon is equal to the time it takes to complete an orbit around its parent planet. Consequently, a season roughly lasts for about 7.5 Earth years on Titan, which makes it difficult to observe a seasonal change through a probe.  

Titan, the Second Largest Moon of our Solar System

Christiaan Huygens, a Dutch Astronomer, was the man who discovered Titan in 1655. It is mostly made up of ice and rocky material while its atmosphere is primarily composed of Nitrogen. It is the only object in space (other than Earth) where stable bodies of surface liquid have been confirmed. It is also the only known moon with a dense atmosphere. It is the 2nd largest moon of our Solar System after Ganymede (Jupiter’s moon). It is 80% more massive than the Earth and appears 11.4 times larger in the sky than the Moon from Earth. A lot of its climatic features, including rain and wind, resemble with the ones we have on Earth. For example, the Methane Cycle on Titan is analogous to the Water Cycle on Earth.    

Discovery of the Cassini Spacecraft

Recently, astronomers detected a slick shimmer on the North Pole of the Saturnian moon. It is being considered the first evidence of the start of summer in the Northern Hemisphere. Despite the fact that scientists observed a ‘Spring Equinox’ in 2009 and then 2011, they were unable to find the rains expected in the north of the Saturnian moon. Rajani Dhingra, a Physicist from the University of Idaho, acknowledged that by saying,

“The whole Titan community has been looking forward to seeing clouds and rains on Titan’s north pole, indicating the start of the northern summer, but despite what the climate models had predicted, we weren’t even seeing any clouds. People called it the curious case of missing clouds.”

The researching team made this important breakthrough through a detailed analysis of a Cassini image, which was captured on 7th June 2016. The Visual and Infrared Mapping Spectrometer (VIMS) instrument of the spacecraft was used for capturing this image as it can pierce through the hazy atmosphere of Titan. They discovered a strange shining region (covering an area of 120,000 square kilometers) that was missing in all the previous or subsequent images. Researchers talked about that and said,

“Based on the overall brightness, spectral characteristics, and geologic context, we attribute this new feature to specular reflections from a rain‐wetted solid surface like those off of a sunlit wet sidewalk.”

Methane Rainfall on Titan

The paper explains that such a region is produced when Methane rainfall onto a rough, pebble-like surface, which is followed by a period of evaporation. Although scientists have been predicting this rainfall for many years now, they lacked physical evidence to strengthen this idea. According to several theoretical models, astronomers should have seen this concept much earlier in the Titan’s season but unfortunately, that didn’t happen. The detection of rainfall in the Southern Hemisphere was also used as a reference that this rainfall will eventually take place.

Despite all the predictions, the missing rain was turning into an irritating mystery that has been solved by this latest study. Scientists believe that this finding will prove extremely beneficial for figuring out more information about Titan’s climate. Having said that, the reason for this delay is still unknown to humanity. Dhingra remarked about that in the following words:

“We want our model predictions to match our observations. This rainfall detection proves Cassini’s climate follows the theoretical climate models we know of. Summer is happening. It was delayed, but it’s happening. We will have to figure out what caused the delay, though.”

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