The Solar System (Saturn)

Saturn, captured by Cassini.
Credits: ESA/NASA

        Saturn, the 6th planet, coined after the Roman god of agriculture and wealth, the ringed beauty of the sky, is also a fascinating wonder. Mapped by the ancient roamers of Earth, Saturn was only clearly viewed, when Galileo observed the giant planet through a telescope in 1610. Similar to Jupiter, Saturn has rings, has loads of moons, and have bands on the atmosphere of the planet. In addition, Saturn is the least dense, and is even lighter than water! Saturn is also the furthest planet that man can see with a naked eye here on this big blue-green world. With all this said, there's no doubt that Saturn is an amazing planet!

False Color Image
of Saturn's South Pole storm.
Credits: ESA/NASA

        As of all astronomical mysteries, the Big Bang, creation of the solar system, the formation of humans are still beyond reach, the formation of our planets like all these mysteries have theories that tie into them. There are three major models that infer the creation of the planets after the sun had came to life. The core accretion model explains the movement of smaller particles sticking together by the force of gravity, and the other lighter materials were pushed away by the sun to where there were lesser influence, thus the gas giants, and other celestial objects formed. However, the core accretion model gives the time of gas giants' formation is inaccurate, as gas filled planets formed rather quickly. The disk instability model describes that the dusts and gases after the sun's creation, clump together to eventually form a planet. This theory gives a more corrected timing for gas planets' formation. The last and third idea is the pebble accretion model. This model suggested that pebbles formed by collisions were the key of gas giants. This model gave gas giants 1000 times the speed over the other models, which agrees with data obtained about the formation of our Solar System's gas giants.

Saturn's Rings
Credits: ESA/NASA

The Keeler Gap in the rings
Credits: ESA/NASA

       Saturn has an atmosphere that composes of many materials, mainly of hydrogen and helium, but ammonia and water ice are also present. Like Jupiter, Saturn had the right ingredients to become a star, just not enough. However, contrast to Jupiter, the bands of Saturn are not brightly distinguished from one another, although the bands do move at different (intense) speeds, parallel to the equator. Like Jupiter, Saturn has occasional storms that rips across the surface of the atmosphere, and many great storms have come and go on the planet. One of windiest places in the Solar System, Saturn boasts speeds up to 1800 kilometers and hour (losing to Neptune's 2,200 km/h winds).

Titan flies over Saturn.
Credits: ESA/NASA

     The most spectacular "valuable" of Saturn is its colorful rings that encircles the planet. The rings are made of rocks that were broken apart by Saturn's immense gravity, and materials, such as water from the planet's 60+ moons (for example, one moon, Enceladus, sprouts water from the Southern Hemisphere that feeds the rings). The rings are made of many layers, and extend up to 175,000 miles from the planet (but only 30 feet high!). The layers are named in the order they were discovered, and there are Rings A-G (the main rings are Rings A-C), and the Phoebe ring. There is a gap between Ring A and B, and is it known as the Cassini Division. Each ring move differently around the planet, and in a thirty year system, the rings tilt (so at mid-way, Earth observers cannot see the rings). The rings also have tiny moons that sweeps the materials aside of its orbit (but Saturn's gravity pulls it back), like Daphnis, a tiny moon in the Keeler Gap in the A ring. Recent studies shows that Saturn's rings are always changing, losing it materials, and gaining them back. Maybe one day our beautiful Saturn may lose its rings!

Enceladus and Pandora
with Saturn's rings.
Enceladus is in the foreground
and has geysers on its South Pole.
Credits: ESA/NASA

      Saturn's magnetosphere, is smaller compared to the mighty Jupiter, but its magnetic field is just as spectacular (and powerful, it's still 578 times stronger than Earth's!). It get beautiful wavy aurorae from interactions with its moons, rather than the interactions with the solar wind. Data received from the Cassini Probe, shows that these Saturn (and Jupiter) aurorae are caused by a mixture of particles ejected from the planet's moons, and the fast rotation speed of the magnetic field. When these materials interact with the magnetic field, a charged electrical force is created, and spirals down the magnetosphere, and into the planet. Studies have shown that Saturn and Jupiter aurorae, do not have influence from the solar wind, which scientists still do not have a complete explanation for this phenomenon.

A large storm appears on Saturn
Credits: ESA/NASA

      Although it is confirmed that Saturn is not habitable, its moons might contain life. Enceladus and Titan, two of Saturn's largest moons may hold the key to presence of life on the planet. Enceladus, a small icy moon, has a thick 30-40 kilometer crust filled with ice, but under this crust is a ocean of liquid water. Cracks and crevices that cut within the crust gives evidence that the moon is active. Enceladus has geysers at the South Pole, where water erupts from the surface. During its mission, Cassini flew through one of the geyser explosions of Enceladus, and detected salty water along with some organic molecules. Although temperatures on Enceladus are extremely cold, life could still exist (some bacteria and simple micro-organisms can live at this temperature). Next up, Titan. Titan is engulfed by a blanket of gas, an atmosphere that's thicker than the Earth's. Mainly made of nitrogen and methane, organic materials exists when the sun ray's break down the methane. These materials are thought to then to rain down to the surface. Powerful winds and ice volcanoes rule the surface, as well as sand that like to bunch up together. Temperatures are freezing cold on Titan, but lakes and rivers containing methane and ethane exists.

Sunlight reflects off a methane/
ethane lake on Titan
Credits: ESA/NASA

      One famous spacecraft that studied Saturn was Cassini-Huygens. The spacecraft was a joint corporation between NASA, the European Space Agency, and the Italian Space Agency. The Cassini probe was named in honor of Giovanni Cassini that studied Saturn's rings, and the gaps between the layers. The spacecraft also carried a lander, Huygens. This lander was named after Christiaan Huygens, who discovered the true shape of Saturn, and the moon Titan. Cassini outlived it's 3 year life, to its 13 years of service. Cassini was the first spacecraft to fully orbit Saturn (other probes, like the Voyagers flew past it), and the Huygens probe was the first to land on another planet's moon. Cassini explored many of the moon, including getting a bath from an Enceladus geyser. Cassini also explored the wondrous hexagon on the planet's north pole, took multiple daring dives through the rings, and at last, burned up in the atmosphere to preserve contamination of the moons. Huygens on the other hand took a jump into the dusty atmosphere of Titan, and detected its atmosphere composition. The probe also took a picture of the surface, and took measurements of the surface of Titan. In less than 5 hours, the probe lost contact, but what it had  discovered is truly fascinating.

North Pole and the Hexagon
Credits: ESA/NASA

       During Cassini's 13 year life orbiting Saturn, Cassini convinced that Saturn's moons are more habitable than previously thought. Cassini also watched Saturn's rings grow and shrink, especially the F ring, which features of the ring from the Voyagers were gone when Cassini arrived. The spacecraft spied on collisions of meteoroids with the rings, and the effects (it is now known that Saturn gets about the same meteoroid strikes as of Earth). Cassini's dives gives a better shot and understanding of the inner ring's composition and detail. Cassini also discovered many new moons, and guided scientists with the specs of them. Data from the spacecraft gives a hint to the interior of Saturn, and the process of the solar system's birth.

Picture taken after
touchdown of Huygens
Credit: ESA/NASA

         With combined data from the Huygens probe that landed on Saturn's largest moon, Titan, we now know that Titan is the most Earth-like celestial body in the solar system. We know its atmosphere composition, the tiny aerosols chemical makeup, and the visuality from the surface. Nevertheless, falling through the thick atmosphere of Titan is a long experience--it took the lander 2 and a half hours to burn past its thick air shield, and survived another 72 minutes on the surface. With all this said, the probe made history and helped Earthlings understand the conditions of Titan. Cassini, orbiting above its harsh climate, provided clues to an underground ocean, high winds, its surface through infrared (and other "visual" wavelengths) topography, and the hint of a high chance that life may exist on the moon.

Descent through Titan.
Credit: ESA/NASA 

Watch what Huygens saw as it descended down to the surface:
https://youtu.be/svmGxFaGILY

Radar Echos recorded be the Huygens 

Probe was translated into audible noise.

This was recorded as the probe descended down 

the last kilometers of Titan's thick atmosphere.

There is no video, only audio.

Credits: NASA/ESA

References:

Ford, Dominic. "Saturn" 6 August 2019. In-The-Sky. 
https://in-the-sky.org/article.php?term=Saturn

"Saturn-Jewel Of Our Solar System" 10 February 2019. NASA. 
https://solarsystem.nasa.gov/planets/saturn/overview/

"Saturn" 25 April 2019. NASA.
https://solarsystem.nasa.gov/planets/saturn/in-depth/

Nelson, Jon. "NASA's Cassini Finds Saturn's Rings Coat Tiny Moons" 28 March 2019. Jet Propulsion NASA.
https://www.jpl.nasa.gov/news/news.php?feature=7360

"Scientists Finally Know What Time It Is On Saturn" 18 January 2019. NASA Science Solar System Exploration. 
https://solarsystem.nasa.gov/news/814/scientists-finally-know-what-time-it-is-on-saturn/

"Saturn 101" National Geographic.
https://www.nationalgeographic.com/science/space/solar-system/saturn/

Cain, Fraser. "Formation of Saturn" 3 July 2008. Universe Today.
https://www.universetoday.com/15385/formation-of-saturn/

Redd, Nola. "How Did the Solar System Form?" 1 February 2017. Future PLC.
https://www.space.com/35526-solar-system-formation.html

Lewin, Sarah. "To Build a Gas Giant, Just Add Pebbles" 19 August 2015. Future PLC.
https://www.space.com/30292-gas-giant-planet-formation-pebbles.html

"Cassini-Huygens" European Space Agency. 
https://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Saturn_s_atmosphere

"Cassini 10 Years at Saturn Top 10 Discoveries" 19 March 2019. NASA Science Solar System Exploration.
https://solarsystem.nasa.gov/news/12892/cassini-10-years-at-saturn-top-10-discoveries/

"Cassini" 28 March 2019. NASA Science Solar System Exploration.
 https://solarsystem.nasa.gov/missions/cassini/overview/

Howell, Elizabeth. "Cassini's 13 Greatest Discoveries During Its 13 Years at Saturn" 13 September 2017. Future PLC. 
https://www.space.com/38142-cassini-greatest-saturn-discoveries.html

"Cassini--Huygens Probe" 4 September 2018. NASA Science Solar System Exploration.
 https://solarsystem.nasa.gov/missions/cassini/mission/spacecraft/huygens-probe/

"Huygens: The Top 10 Discoveries At Titan" 11 January 2017. European Space Agency. 
http://sci.esa.int/cassini-huygens/55221-huygens-titan-science-highlights/