Gas Giants

A Gas giant is a large planet mainly composed of gases like hydrogen and helium. Gas giants may have a rocky or metallic core. They are also called Outer Planets or the Jovian Planets.

Interesting Gas Giants Facts

  • Gas giants as the name suggest are planets made up of dust and gas.
  • They are mostly composed of hydrogen, helium, ammonia, methane, water or other gases.
  • They are known to have a lot of moons, unlike terrestrial planets.
  • There are four gas planets in the solar system namely – Jupiter, Saturn, Uranus, and Neptune.
  • Scientists have discovered thousands of large gaseous planets outside the solar system.
  • All the gas giants have a very short duration or period of rotation that is they rotate about their own axis very quickly.
  • These planets take a longer time to orbit Sun because of their great distance from the Sun.
  • They are not only made up of Gas, beneath their atmospheres of Jupiter and Saturn layers of hydrogen and liquid metallic hydrogen is found.
  • The metallic hydrogen layer of Jupiter and Saturn conduct electricity.
  • The temperature of the cores of these gas giants is very high due to high pressure. Jupiter’s core temperature is around 35,700°C. The core of Saturn is estimated to be very hot at around 11,700 °C.

What are Gas Giants?

Gas giants as the name suggest are planets made up of dust and gas. They lack a definite and solid surface and are the outer planets in the solar system. They are different from terrestrial planets as terrestrial planets have definite surfaces along with physical features like mountains, volcanoes, craters, etc. Whereas gaseous planets like all these features, they are mostly composed of hydrogen, helium, ammonia, methane, water or other gases.

However, they are not entirely gas and do contain solid materials like metallic hydrogen, water ice, or a small core. Gas giants are made up of all of the basic elements that a star contains and hence they are also referred to as Failed Stars. They do not have a proper atmosphere. They are known to have a lot of moons, unlike terrestrial planets.

Planet Jupiter has as many as 79 moons. Some of these moons are even larger than the planet Mercury. These moons are also been explored as they have conditions that show that they could harbor life. Jupiter’s moon, Ganymede, and Saturn’s moon, Titan, are examples of such moons. They are much larger in size.

All the gaseous planets are known to have at least some kind of ring system. The most prominent and the largest ring system in the solar system belongs to Saturn. Gas giants are much less dense than terrestrial planets.

There are four gas planets in the solar system which include – Jupiter, Saturn, Uranus, and Neptune. Uranus and Neptune have a more bulky structure as compared to Jupiter and Saturn. Hence, they are also known as ice giants. All the gas giants are separated from the terrestrial planets by an elliptical disc called the Asteroid belt.

The Asteroid belt lies between the orbits of Mars and Jupiter. They are far away from the sun and hence show relatively lower temperatures than terrestrial planets. As the orbits are large they take a lot of time to revolve around the sun once. All the gas giants have a very short duration or period of rotation i.e. they rotate about their own axis very quickly.

The solar system contains only four gaseous planets. However, scientists have discovered thousands of large gaseous planets outside the solar system and they are being studied to find out more about the origin of the solar system. Let’s know more about Four Gaseous planets of our solar system.

Jupiter

Jupiter is the fifth planet from the sun and the first of the gas giants. It is also the largest planet in the solar system. It was first observed through a telescope by Galileo Galilei. It has been named after the Roman King of Gods. It is the third brightest object in the night sky as seen from the earth after the moon and Venus.

Size

It is 778.5 million km away from the Sun. It takes around 12 years to revolve around the sun once. Jupiter is so massive that the mass of the planet is more than two and a half times the mass of all the other planets in the solar system combined.

The planet has a mean radius of 69911 km. It takes 9 hours and 56 minutes to rotate about its axis. The temperature on Jupiter is -145°C. Jupiter has an inner core the temperature of which can rise up to as high as 24000 °C.

Appearance

Jupiter is also known to have a ring system commonly known as the Jovian ring system. However, these rings are faint or not as prominent as those of Saturn. Jupiter is famous for its great white spot. It is a white patch on the planet which is actually a storm that has been going on the planet for at least the last 450 years. Jupiter basically has a striped pattern of white, brown and orange

Satellites of Jupiter

Jupiter is known to have 79 moons. The four largest moons are Io, Europa, Ganymede, and Callisto. Ganymede is the largest moon in the solar system. It is also larger than the planet Mercury.  The moon Io has the most active volcano in the solar system.

Exploration and Life on Jupiter

It is believed that water exists on the surface of Europa. If this being true then it is quite likely that Europa could sustain life. Jupiter has been visited by several spacecraft and probes. The first spacecrafts to fly around Jupiter were Pioneer 10 and 11 and Voyager 1. The only spacecraft to be orbiting Jupiter currently is Juno by NASA. 

No human being has ever visited Jupiter and no evidence of life has been found on the planet yet. However, scientists believe that it is unlikely that Jupiter could support life because of the extremities in its conditions.

As the largest planet of the solar system, Jupiter has found a place in Earth’s pop culture as well. It is considered as a God in many cultures. It has also found mentions in numerous movies, books, and TV shows.

Saturn

Saturn is the sixth planet from the sun and the second-largest planet in the solar system. Galileo Galilei was the first person to observe Saturn through a telescope. Saturn is the last of the planets to be directly visible from the surface of the earth.

Size

It has been named after the Roman God of agriculture. This planet is 1.43 million kilometers away from the Sun. The radius of Saturn is 58,232 kilometers. It takes 29 and a half years to revolve around the sun once. It takes nearly 10 hours and 42 minutes to rotate about its own axis.

Physical characteristics

Saturn may have a small rocky core lying at its center, but this is not confirmed. Saturn is the least dense of all the other planets. It is the only planet in the solar system to be less dense than water.

Unique ring of Saturn

Saturn is a yellowish Brown or butterscotch in color. The planet is most famous for its prominent ring system which makes it the most easily distinguishable planet in the solar system.

These rings are made of ice particles, dust, debris, and other celestial material. There are seven main rings in this ring system. Many times, Saturn is also called the ‘Ringed planet’ or the ‘Jewel of the Solar System’.

Satellites of Saturn

Saturn is known to have at least 150 moons out of which just about 50 have been officially named. These moons vary greatly in size and shape. The largest of Saturn’s moons is Titan. It is the second-largest moon in the solar system and is larger than the planet Mercury.

Titan has been a subject of great speculation because it is believed to have oceans or other water bodies under its surface. If this is so then Titan may be able to sustain life in the future. The temperature on Saturn can be as low as – 270°C.

Exploration and Life on Saturn

Saturn has been visited by four spacecrafts three of which were flybys. Cassini by NASA is the only spacecraft that has orbited Saturn. Various future missions for sending spacecrafts to Saturn have been proposed but none of them have been approved so far.

Extreme conditions Saturn is unlikely to support life. However, its moons are believed to be suitable for the existence of life. Investigation of life on Saturn and its moon is being conducted.

Saturn has found a great space in pop culture because of its unique nature. The day Saturday is also named after Saturn in almost all cultures.

Uranus

Uranus is the seventh planet from the sun and the third largest planet in the solar system. It has been named after the Greek deity of God, the father of Cronus that is Saturn, and the grandfather of this that is Jupiter. It is the only planet that has been named after a figure from Greek mythology.

Size and Distance

Uranus is 2.871 billion kilometers away from the sun. It takes nearly 30,688 days i.e. approximately 84 years for Uranus to revolve around the sun. It takes 17 hours and 14 minutes for Uranus to spin about its own axis. The diameter of Uranus is 51118 km. It was the first planet that was discovered with the help of a telescope.

Composition

Uranus is mostly composed of hydrogen-helium and methane. It is bulkier than Jupiter and Saturn and contains a lot of ice. Hence along with Neptune Uranus is called an ice giant. Uranus is a unique planet as it revolves around the sun in a clockwise direction like Venus. These two are the only planets to do so.

Rings and Satellites of Uranus

Uranus also rotates on its side because of the near 90° tilt. This planet has 13 rings. These rings appear to be vertical like those of Jupiter and Saturn. It is also because of the large tilt. This state is also responsible for Uranus showing unique and dynamic magnetic behavior.

Uranus has 27 moons all of which have been named after characters from plays by William Shakespeare and Alexander Pope. The largest moon of Uranus is Titania. It was one of the first two moons of the planet to be discovered, along with Oberon. Due to its large distance from the Sun, Uranus is a very difficult planet to observe and explore.

Exploration and Life of Uranus

Uranus has been visited by only one spacecraft which is Voyager 2 by NASA. It took nearly 9 years for the spacecraft to reach Uranus. It provided great details about the planet’s composition, temperature, atmosphere, wind speeds, moons, etc. No future missions to explore Uranus have been approved yet.

Thus, the only means of exploring and observing Uranus are telescopes on Earth. No evidence of life has ever been found on Uranus and it is also quite likely that life may exist on it in the future. This is because of the large distance of the planet from the sun and the conditions on it. It is also because Uranus is not like all the other giant planets, it lacks a definite surface. 

Neptune

Neptune is the 9th planet from the sun and the farthest planet in the solar system. Neptune is named after the Roman God of the sea. Neptune is the smallest of the gas planets. It is nearly 30 astronomical units away from the Sun. Galileo Galilei was the first person to observe Neptune through a telescope.

Size and Physical characteristics

It takes 164.8 years for Neptune to orbit around the sun once. The period of rotation of the planet is 16 hours and 6 minutes. The equatorial radius of the planet is 24800 km. The temperature on Neptune can be as low as -214°C. Like Uranus, Neptune also has a large field and hence it shows many magnetic variations as well.

Appearance, Composition, and Rings

Neptune is mainly composed of hydrogen, helium, and methane. Along with Uranus, it is also called an ice giant. Neptune has a striking deep blue color that distinguishes it well from the other planets. This is because of the presence of gases like Methane that absorb the red light and give out blue light.

It also has a big white spot on it which is similar to the Great White Spot on Jupiter. There are several small white spots that come and go. These are all storms. Like the other gas planet, Neptune also has rings. These rings are very faint. Some of them are even incomplete or irregular. Not much is known about the Neptunian ring system, but it has been confirmed that there are five primary rings.

Exploration and Life on Neptune

The first spacecraft to visit Neptune was launched in 1977 by NASA which also visited Jupiter, Saturn, and Uranus. Another spacecraft called Pioneer 10, on the way to Aldebaran i.e. the red star, crossed the orbit of Neptune in 1983.

Neptune has only been visited by one spacecraft that is Voyager 2 by NASA in 1989. Voyager 2 is also the only spacecraft to have visited Uranus. Voyager 2 took close to 12 years to reach Neptune from Earth.

No human being has ever visited Neptune. No evidence of life has been found in Neptune either. Due to the large distance of Neptune from the sun and the extreme conditions in its atmosphere, it is nearly impossible for life to exist on this planet. Life could, however, exist on one or more of its moons. Neptune has found a place in the earth pop culture as well why have inventions in movies, books, TV, etc.

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