Titan - Saturn biggest Moon

Introduction

Titan, Saturn's biggest moon, is an ice planet with a golden hazy atmosphere that totally obscures its surface. Titan is our solar system's second-biggest moon. Only Jupiter's moon Ganymede is slightly bigger, by 2%. Titan is larger than the moon of Earth and even larger than the planet Mercury.

This massive moon is the only moon in the solar system with a dense atmosphere, as well as the only world in the solar system with standing bodies of liquid on its surface, such as rivers, lakes, and seas. Titan's atmosphere contains mostly nitrogen with a tiny quantity of methane, just like Earth's. It is the only other location in the solar system known to have an earthlike water cycle, with liquids falling from clouds, flowing over its surface, filling lakes and seas, and evaporating back into the sky (like Earth's water cycle does). Titan is likewise supposed to contain a water ocean under its surface.

Size and Distance

Titan is about half the size of Earth's moon, with a radius of around 1,600 miles (2,575 kilometers). Titan is 759,000 miles (1.2 million kilometers) away from Saturn, which is 886 million miles (1.4 billion kilometers) away from the Sun, or 9.5 astronomical units (AU). The distance between the Earth and the Sun is one AU. The Sun's light takes roughly 80 minutes to reach Titan and sunlight are around 100 times fainter there than on Earth due to the distance.

Figure 1 Titan, the moon of Saturn, source NASA Visualization Technology Applications and Development (VTAD).

https://solarsystem.nasa.gov/resources/2349/titan-3d-model/

Orbit and Rotation

Titan completes a full orbit of Saturn every 15 days and 22 hours. Titan is likewise tidally locked in synchronous rotation with Saturn, which means that, like the Earth's Moon, Titan always faces Saturn as it circles. Saturn orbits the Sun in roughly 29 Earth years (a Saturnian year), and its axis of rotation is inclined similarly to Earth's, resulting in seasons. The longer year on Saturn, however, results in seasons that endure longer than seven Earth years.

Titan Seasons

Titan's seasons are on the same schedule as Saturn's, with seasons lasting more than seven Earth years and a year lasting 29 Earth years. Titan revolves nearly along Saturn's equatorial plane, and Titan's tilt relative to the sun is about the same as Saturn's.

Structure

Titan's underlying structure isn't completely understood, but one hypothesis based on Cassini-Huygens data says Titan has five main layers. The deepest layer is a 2,500-mile-wide (4,000-kilometer-wide) rock core (particularly, water-bearing silicate rock). A shell of water ice surrounds the core, and a unique kind known as ice-VI can only be found at extremely high pressures. A layer of salty liquid water surrounds the high-pressure ice, which is topped by an outer crust of water ice. Organic molecules that have rained or otherwise settled out of the atmosphere in the form of sands and liquids are covered on this surface. A thick atmosphere envelops the surface.

Figure 2 Internal structure of titan.

Formation

Titan's genesis is unknown to scientists. Its atmosphere, on the other hand, gives a hint. The isotopes nitrogen-14 and nitrogen-15 in Titan's atmosphere were detected by many sensors on the NASA and ESA Cassini-Huygens mission. Titan's nitrogen isotope ratio is most similar to that found in comets from the Oort cloud, a sphere of hundreds of billions of icy bodies thought to orbit the Sun at a distance between 5,000 and 100,000 astronomical units (Earth is about one astronomical unit from the Sun—roughly 93 million miles or 150 million kilometers).

Titan's atmospheric nitrogen ratio suggests that the moon's building blocks developed early in the solar system's history, in the same frigid disc of gas and dust that created the Sun (known as the protosolar nebula), rather than later, in the warmer disc of material that Saturn formed from (called the Saturn sub-nebula).

Surface

Titan's surface is one of the most Earth-like places in the solar system, albeit it is much colder and has a distinct chemical. Water ice fulfills the role of rock here since it is so cold (-290 degrees Fahrenheit or -179 degrees Celsius). Titan might have volcanic activity as well, but instead of molten rock, it could have liquid water "lava." Flowing methane and ethane cut river channels and fill vast lakes with liquid natural gas, sculpting Titan's surface. Apart from Earth, no other planet in the solar system has that level of liquid activity on its surface.

Figure 3 Different surfaces of titan taken from VTAD NASA.

https://solarsystem.nasa.gov/resources/2347/titan-surface-3d-model/

Large swaths of black sand spread over Titan's surface, particularly around the equator. The "sand" of these sand dunes is made up of black hydrocarbon granules that resemble coffee grounds. The towering, straight dunes have a look similar to those seen in Namibia's desert. Titan's surface contains few visible impact craters, implying that it is young and that some combination of processes is erasing traces of collisions over time. Earth is similar in that regard; craters are wiped on our planet by the relentless forces of flowing liquid (water in Earth's case), wind, and plate tectonics' recycling of the crust. These forces exist on Titan as well but in different forms. Tectonic forces, which cause ground movement owing to pressures from below, appear to be at work on the frozen moon, however, scientists have found no evidence of plates as on Earth.

Geological features of Titan

Titania, Uranus' biggest and most massive satellite has geological features that are comparable to those of Oberon. The most widespread surfaces found here are heavily cratered plains. Oberon also depicts a worldwide rift valley network linked to tectonics. Titania's image resolution is somewhat greater than Oberon, owes to Voyager 2's proximity to Titania. The most conspicuous class of features on Titania's surface is a significant system of canyons and scarps; shadows show that some of them may be as deep as 3.7 mi (6 km). Plains that are somewhat cratered and smooth are also seen, indicating resurfacing.

 These characteristics suggest that following the severe bombardment (crater formation) phase of their histories, Titania experienced greater geologic activity than Oberon. Rather than terrestrial type volcanic lava, the resurfacing material should be liquid or ice water, ammonia, or methane, perhaps combined with stony debris. These ices may have melted or softened as a result of the impact and/or internal heating, and then erupted and poured over the satellite surfaces, resurfacing them. This process is known as cryovolcanism (also known as water volcanism), and it may have had a role in the geological histories of several of the Jovian planets' satellites.

Figure 4 Examples of the main types of geomorphologic units of Titan as shown in SAR photos. The scale bars are 50 kilometers, and the percentages of world area covered by each major unit are listed below. (Image courtesy of Lopes et al., 2019.)

Figure 5 Global map of titan.

Titan Atmosphere

There are more than 150 moons in our solar system, but Titan is the only one with a thick atmosphere. Titan's atmosphere consists primarily of nitrogen (about 95%) and methane (about 5%), with minor quantities of other carbon-rich molecules. The Sun's ultraviolet radiation and high-energy particles accelerated in Saturn's magnetic field break methane and nitrogen molecules high in Titan's atmosphere. Some of the chemicals created by the splitting and recycling of methane and nitrogen generate smog, a thick, orange-colored haze that makes viewing the moon's surface from space difficult. (Some of the heavier, carbon-rich compounds fall to the moon's smoky surface.)

The research behind life at Titan

Numerous gravity measurements taken by the Cassini mission on Titan indicated that the moon hides a subterranean ocean of liquid water (likely mixed with salts and ammonia). During its descent to the surface in 2005, the European Space Agency's Huygens probe detected radio signals that strongly supported the presence of an ocean 35 to 50 miles (55 to 80 kilometers) beneath the frozen ground. Titan joins a small group of worlds in our solar system that might possibly have livable conditions, thanks to the finding of a vast ocean of liquid water.

Titan's liquid methane and Ethane Rivers, lakes, and seas might also provide a livable habitat on the moon's surface, however, any life there would likely be extremely different from life on Earth. As a result, Titan might possibly hold habitats appropriate for life-both life as we know it (in the deep ocean) and life as we don't know it (on the surface) (in the hydrocarbon liquid on the surface). Titan's complex chemistry and diverse habitats will undoubtedly make it a destination for further research, despite the lack of evidence of life thus far.

Quick Facts

Discovered	March 25, 1655 by Christiaan Huygens
Type	Icy Moon
Diameter	3200 miles (5149.4 km)
Orbital Period	Nearly 16 Earth days
Length of Day	Nearly 16 Earth days
Mass	1.8 times of Earth’s moon
Distance from Saturn	1221870 km
Distance from Sun	1427000000 km (9.54 AU)
Average Density	1.881 times liquid water
Surface Temperature	94 K (-179˚C)
Atmospheric Composition	Nitrogen, methane, traces of ammonia, argon, and ethane
Atmospheric Pressure	1500 mbar