Titan was discovered in 1655 by Dutch astronomer Christiaan Huygens and was the first out of the four moons of Saturn to be discovered around that period. By the time of the 17th century, French astronomer Giovanni Cassini discovered the other moons of the planet and the different divisions of Saturn’s famous ring. It was noted that Titan’s size is larger than the earth’s moon, and, it can easily be seen through the use of conventional binoculars. The entire diameter of Titan is 3,200 miles or 5,150 (km) making it larger than Mercury and smaller than Mars. In comparison to the other moons in the solar system, Ganymede is bigger than Titan. Titan can manage to revolve around Saturn in the length of 16 days. From Saturn, Titan orbits the planet from the extent of 750,000 miles or 1,200,000 (km). Its distance away from the planet enables both the moon and the planet to avoid each other in cases of collision. This also enables the Titan atmosphere to be filled with Saturn’s electrons from its magnetosphere. Due to Titan’s position being in Saturn’s ring plane, it experiences different seasons. The moon is also close to Hyperion, a known outermost moon of Saturn. Titan’s orbit is quite complex due to the lack of a shallow ocean on the moon.
What makes Titan unique from other moons is the fact it has a thick atmosphere. Titan’s atmosphere is orange in color due to the elements comprising the atmosphere. Some of the elements found in Titan’s atmosphere are nitrogen, methane, hydrogen and argon. Nitrogen comprises most of the elements comprising the Titan atmosphere. Apart from the elements comprising the atmosphere, thick layers of clouds and haze also makes it difficult to see Titan’s surface even with a telescope. Scientists are still unsure as to the capacity of Titan to support any life in its land. But, from the recent study, the temperature in the moon is much too low for any life form to exist as it is at least 94 K . It is due to this temperature and the force of at least 1.5 bars or 1,500 hPa that make Titan’s atmosphere denser than the Earth’s atmosphere.
There are various theories as to how Titan originated, but, like the other moons of Saturn, it has been created through Saturn’s’ subnebula around 4.6 billion years ago. Through the different blocks and planetesimals of the subnebula, Titan slowly came to form. But, while the process is undergoing, it is noted that it was also the time wherein the temperatures dropped in the moon due to gravity and radioactive decay. Upon the end of the process, it is said that the moon was created with an inner silicate centre and surrounded by an outer layer made of the same material. It is also said that there is a water-ammonia layer surrounding the moon’s surface.
As of today, there is still no definite conclusion with regards to the origin of Titan’s unique atmosphere. Theories have been raised regarding this issue. One theory was developed in 1981 by Prinn and Fegley, noting that Saturn’s subnebula was strong enough to allow carbon monoxide and nitrogen to survive. With the location of Titan’s orbit at least 20 Saturn radii; it enabled carbon monoxide to be converted to CH4 and nitrogen to ammonia. With this converted elements, it enabled the creation of planetesimals to develop Titan through its hydrates form. The theory was created by Mousis and his team was another possibility, they noted that the subnebula was chaotic to prevent any change of CH4 and ammonia. There are models that indicate that planetesimals were created in Saturn’s feeding area, which enabled the conversion to hydrates that then created Titan. For this model, it would explain the structure of the Titan atmosphere and the formation of the planetesimals which created the moon .
Upon the discovery of the moon, many explorations have been sent to the area to get a closer image of the mysterious moon. The first recorded observation was in 1980 with the Voyager 1, which tried to capture images of the surface but was prevented due to the cloudy sky that caught up with the flyby mission. It has been through rough maps that enabled scientists to note that there are dark regions in the moon’s surface, which depicts the existence of ethane and methane oceans. It is estimated that the dark regions are at least 300 miles in diameter. Through the conclusion that there are ethane and methane oceans in the moon, scientists have noted that methane only exists in small portions in the sky to allow coexistence with a pure methane ocean. Should there have been more, there is a possibility that the ocean would evaporate and allow methane to occur in the atmosphere.
Other scientists have developed several techniques to analyze Titan’s complex atmosphere such as the group of Schaller, Brown and Roe of the California Institute of Technology. Their approach enables them to recognize when exactly the methane clouds form in the atmosphere of Titan. In their study, they have noted that the moon occasionally releases bright methane clouds primarily on its summer seasons. In this season, methane heats up and evaporates to make these clouds. But in every fall and winter season, methane returns back to surface through the form of rain showers and return the liquid to its former channels. Since this liquid is made out of ethane, this creates more channels to allow more liquid to remain on the surface. This is similar to how river channels are created back on Earth. It is also noted that there is a hint of cryovolcanism in the moon. Cryovolcanism is the process wherein volcanoes erupt ammonia and water unlike the usual process wherein hot silicate and sulphur magma bursts out of the volcano. Based on the images taken from the previous explorations and the current inputs coming from the current exploration, Titan’s atmosphere and temperature enabled this cryovolcanism to occur on the moon.
Rain in Titan is extraordinarily rare in the solar system given that only Earth has been recorded to experience rain compared to the other planets and moons. The Earth’s Moon, Mercury, and, Mars do not even experience a chance of rain which proves its rarity. But, compared to the rains experienced in Earth, Titan’s raindrops are much larger compared to the raindrops in Earth. Unlike the Earth’s rains, Titan’s rains are unusually slow and are like snowflakes falling on a serene Earth day. In terms of its winds, Titan’s winds are produced by the gravitational pull of Saturn. This is due to the location of the moon from the Sun. But, most of the winds created in Titan are strong enough to make waves. Another comparison with the Earth’s waves , which are smaller and faster, is that the waves in Titan are taller and slower. Titan’s ocean waves can deliver a powerful force once it touches the surface .
Today, the NASA exploration Cassini-Huygens spacecraft, which is named after the two astronomers who discovered the moons of Saturn, is orbiting the planet to know each puzzle around Titan. The expedition had begun its journey in October 1997 and is supported by NASA, the European Space Agency and the Italian Space Agency. In 2004, it dropped a probe named Huygens to examine the upper atmosphere of the moon and capture photos upon its decent in the cloudy atmosphere. The unique capability of the Huygens enables it to check the elements within the sky and analyze the components comprising it and the surface. The Huygens is also capable of bouncing and floating to cater any surface it passes into. The only downside to the space probe is that it can only send information every few hours due to its battery life. With the haze surrounding the atmosphere, it makes it difficult for the space probe to use solar energy to recharge . Once the spaceship returns, it is without a doubt that scientists will be closer to answering most of the questions that have been debated on since the start of time. But, before it could even return, Titan’s mysteries would continue to branch out into more questions that would certainly explain the science behind the galaxy.
Elkins-Tanton, Linda. Jupiter and Saturn. New York: Infobase Publishing, 2006. Print.
Horneck, Gerda and Petra Rettberg. Complete Course in Astrobiology. Weinheim: John Wiley and Sons, 2007. Print.
Kerrod, Robin. Saturn. Minneapolis: Lerner Publications, 2000. Print.
Walter, Katie. A Speckled Look at Saturn's Moon, Titan. Science and Technology Research. Livermore: Lawrence Livermore National Laboratory, 2000. Print.