Gas Giant Planets
What makes the Sun special in this gigantic universe is that it has developed and evolved in the life perspective. It has always been a mystery how the Solar System was formed since it was discovered by humanity. The understanding of its evolution and origin is very limited nowadays. The theories of the Solar System formation are not fully explained and it is still impossible to explicate them now. Therefore, there is no elucidation that may be thoroughly discussed and stated as absolute. Scientific cycling through prediction, hypothesis, theory, and measurement are the only methods of this progress (Woolfson 4).
Here are the most popular theories on how the Solar System was formed.
- Nebular hypothesis – the most accepted and current theory. It states that the Solar System was formed by a gravitational collapse of a big cloud of molecules. Firstly this theory was developed by I. Kant, at the end of the 18th century;
- Tidal theory – states that the planets were formed by the pieces of the Sun ripped by another star;
- Interstellar cloud theory – states that there was a cloud of interstellar dust and gas, through which the Sun passed and the planets formed;
- Protoplanet theory – states that the planets and the Sun within the same cloud were combined individually;
- Capture theory – asserts the tidal interaction between a low-density protostar and the Sun formed the Solar System.
In the earliest writings that are recorded, astronomers, scientists, and philosophers from the past have been looking for the facts and answers on how everything was formed. Despite the authoritative model of the Universe formation, scientists accept the Nebular hypothesis. For many years they did not pay attention to it, but now it is considered as a definitive model. This theory shows that the Solar System began existing around 4.6 billion years ago and this process started when the molecular cloud part of interstellar gas collapsed. According to the Nebular hypothesis, it was filled with dust, particles of ice, rocks, and other substances. After the turbulence, which heated this cloud up, it collapsed and finally turned it into a star (“Solar System Formation” 2).
The Sun formation took the most of this cloud. And around the Sun, the other material formed a planetary disc, also known as solar nebula, which later went into the genesis of planets and other objects. The formed solid objects, that become bigger as the other particles collide, are attracting ice and dust by the influence of gravitation. These objects develop into cores of the planets and many of them leave the Sun System and become comets. Due to collision and radiation between the objects, these formations of ice, dust, and rock become different planets. As scientists determine, it has been forming and developing through millions of years. The planetesimals like asteroids, that never got large were formed from the same nebula, are often called “failed planets” (“Solar System Formation” 4).
Pierre-Simon Laplace was stating that the protosolar cloud or nebular cloud cooled and contracted, shedding and flattering material rings and later collapsed becoming a planet system. Within the 20th century, many scientists were challenging this theory, proposing several models, in order to replace it.
Despite the fact that this nebular hypothesis theory is not fully explained by astronomers and scientists, it is still approved. One of the facts that became an issue in this theory is the axial tilts of the planet. Nowadays, with all the advantages of technology, the astronomers may study planets that are extrasolar and they have determined some irregularities that put the nebular hypothesis to doubt. Since the end of the space age (1950s) and later extrasolar planet discovery (1990s), all these models were refined and challenged for the new observations (Cessna, 2).
In the Solar System, there are two groups of planets – the outer and the inner ones. The outer planets are the following – Saturn, Jupiter, Neptune and Uranus and the inner ones are Mars, Earth, Venus, and Mercury, which are the closest four planets to the sun. These groups of planets are detached by the belt of asteroids.
Both types of planets are distinguished by certain features. For instance, the inner planets or terrestrial planets have a paved surface and have much in common with the Earth. They are quite close to each other, but with different distance between in space terms. The outer planets, also known as Jovian planets, have no paved surfaces, are gaseous, and have only liquid cores. They are much bigger, containing 99% of the mass of the celestial object (“The Outer Planets \ The Gas Giants” 4).
The largest planet in our Solar System is Jupiter; its mass is three hundred times bigger than the mass of the Earth. It also has 63 moons; no other planet has more. Jupiter is considered the brightest object in the sky and has quite a stormy atmosphere. One of the storms on its surface, called Great Red Spot – is the size of the planet Earth. The planet’s core is not solid; it is liquid and consists of hydrogen. It seems really big because of its magnetic field. Jupiter consists of approximately 90% of hydrogen and 10% helium with traces of methane, water, ammonia and "rock". (“The Outer Planets \ The Gas Giants” 2)
Saturn is one of the biggest planets too, as it is hard to miss with its huge rings around. Till the year of 1977, astronomers did not know that there are other ring planets, like Uranus. Sooner, the rings of the planets were discovered around both Neptune and Jupiter. Saturn has such a big amount of gas that if the planet had the seas of water, they would float in this gas. Its atmosphere keeps the heat from escaping into space and its surface stays warm inside for billions of years. Saturn is very far from the Sun and for sure the planet is very cold; it takes around 30 our years for this planet to go around the Sun (“Outer Planets” 13).
Uranus is the smallest of the outer planets and is the only planet that rotates on its side. There are a couple of theories on why it rotates that way, but there is no absolute explanation. One of the suggestions was that the planet was suffering a big collision, but also many scientists think that the unusual rotation is caused by small shifts during its formation. Uranus' atmosphere is about 83% hydrogen, 15% helium and 2% methane, and it is rapidly blown around clouds. As the Sun is at the low Uranian latitude, it causes the pronounced day\night weather effects (Amett 7).
Neptune is the last planet from the outer planets. It is known by its fast and the strongest winds that sometimes may reach up to 1,200 mph and the areas with the strongest pressure called Dark Spots. As other outer planets consist of helium and hydrogen, Neptune and Uranus have a huge amount of ices in them. These ices consist of ammonia, water, and methane. Methane is the element that gives these two planets a blue color. Neptune completes an orbit every 165 years. It takes about 16 hours to turn the planet around its axis. It has 13 moons, including one that consists of nitrogen eruptions (Amett 5).
The Gas Giants are huge if to compare to inner planets, and are made up mostly out of gas, so they do not have the solid surfaces. Despite some similarities, every planet in the outer system has its own characteristics, but none has the ability to support life, but the Earth.