In our solar system, there are four planets that are made out of gas. These planets are called the Gas Giants. Another name for these is the Jovian planets (Jove is Jupiter’s Latin name). Astronomers have also discovered planets outside of our solar system. These are known as exoplanets. Some of these exoplanets are made out of gas, but we know less about them than we do about our Gas Giants.
The planets in our solar system that are made out of gas are the four Gas Giants; Jupiter, Saturn, Uranus, and Neptune. There are also exoplanets (which are planets outside our solar system) that are made of gas. These include 51 Pegasi b, KELT-9 b, and Kepler-7 b.
This article will give you information and detail about our solar systems amazing Gas Giants but also gives information on some of the better-known gaseous exoplanets. Let’s take a look at them…
1. Jupiter
How Did Jupiter Get Its Name?
In ancient Roman mythology, the king of the gods was named Jupiter. As Jupiter is the largest planet in our solar system, astronomers decided it was fitting to name it after this Roman god king.
Features And Facts About Jupiter
- Size: Jupiter has a diameter of 88,846 miles. Earth only has a diameter of 7,918 miles, so Jupiter is over 11 times as wide as the Earth! Jupiter’s mass is 318 times more than that of the Earth.
- Distance from the sun and surface temperature: Jupiter is further from the sun than the Earth. In fact, it is 5.1 times further away. What does this mean for the surface temperature of Jupiter? At Jupiter’s surface, the temperatures are only about -160°F, even with the internal heat generated by the gradual shrinking of Jupiter’s core.
- Orbit and rotation: It takes 12 times longer for Jupiter to complete one orbit around the sun. This means that one year on Jupiter is the equivalent of 12 years on Earth. Although its years are long, Jupiter’s days are shorter because its rotational speed is faster. One day on Jupiter is just less than 10 hours long.
- Discovery of Jupiter: Jupiter has been known since ancient times. Its size makes it very observable, even with the limited technology of these ancient times. However, the first official and detailed observations of Jupiter were made by none other than Galileo Galilei in 1610.
Composition Of Jupiter
Jupiter is composed mainly of two elements. These are hydrogen and helium, which are gases. This is how Jupiter became known as a Gas Giant.
Note: This post may contain affiliate links which will take you to online retailers that sell products and services. If you click on one and buy something, I may earn from qualifying purchases. See my Affiliate Disclosure for more details.
While Jupiter’s atmosphere may be gaseous, this is not true for the deeper regions of the planet. Here, the pressures exerted by the vast mass of Jupiter actually compress the hydrogen and helium gases into a liquid state.
Jupiter has a dense core. This may be made up of solid rocks and ice, or it could be a thick liquid, and it is surrounded by a thick layer of liquid hydrogen and helium, accounting for 80-90% of the entire planet’s diameter.
Then the gaseous outer layers of Jupiter form bands as the gas clouds are moved along the East-West axis by powerful winds. These bands are different colors because they contain different substances (although they are mainly hydrogen and helium).
Jupiter’s Rings
As we discovered in 1979, Jupiter also has rings—three of them—but they are very hard to see, despite their size. The main ring is 4,000 miles wide, although it is flat (20 miles thick). The middle halo ring is 12,000 miles thick. The gossamer ring (it’s actually made up of 3 separate rings) is 61,400 miles wide but almost transparent.
Jupiter’s Moons
Jupiter probably has over 79 moons, although only 58 of these have been confirmed and named.
| Jupiter’s Confirmed And Named Moons | |||
| Adrastea | Aitne | Amalthea | Ananke |
| Aoede | Arche | Autonoe | Callirrhoe |
| Callisto | Carme | Carpo | Chaldene |
| Cyllene | Dia | Eirene | Elara |
| Erinome | Ersa | Euanthe | Eukelade |
| Eupheme | Euporie | Europa | Eurydome |
| Ganymede | Harpalyke | Hegemone | Helike |
| Hermippe | Herse | Himalia | Io |
| Iocaste | Isonoe | Jupiter LI | Jupiter LII |
| Kale | Kallichore | Kalyke | Kore |
| Leda | Lysithea | Megaclite | Metis |
| Mneme | Orthosie | Pandia | Pasiphae |
| Pasithee | Philophrosyne | Praxidike | Sinope |
| Sponde | Taygete | Thebe | Thelxinoe |
| Themisto | Thyone |
If you are in the market for a new party trick, you can memorize all of these names. But mostly, people just talk about Jupiter’s four largest moons: Io, Europa, Ganymede, and Callisto. According to NASA, all of these moons hold a title in our solar system. These titles make these moons more scientifically relevant than the others.
- Io has the title of being the “most volcanically active body in the solar system”.
- Europa is possibly the “best place to look for environments where life could exist”.
- Ganymede is known to be the “largest satellite in our solar system”.
- Callisto is known as the “most heavily cratered object in our solar system”.
2. Saturn
How Did Saturn Get Its Name?
Saturn was also named after an ancient Roman god. In fact, all of our planets, with the exception of Earth, are named after ancient mythical gods. Saturnus is the name given to the Roman god of agriculture and the harvest.
Features And Facts About Saturn
- Size: Saturn is the second-largest planet in our solar system, measuring 72,367.4 miles in diameter. This means that Saturn is just over 9 times wider than Earth.
Saturn has only about 95 times greater mass than the Earth, despite being so much bigger. This is because Saturn has a very low density—less than water. According to NASA, Saturn “could float in a bathtub if such a colossal thing existed”.
- Distance from the sun and surface temperature: Saturn is 9.5 times further away from the sun than the Earth is. As you can imagine, this distance from the sun means that Saturn’s surface temperature is extremely low. It is -288°F, and most of this heat is produced in Saturn’s own core.
- Orbit and rotation: Saturn is further from the sun, so it takes longer to complete an orbit (or a year). 29 Earth years pass before a single Saturn year has been completed. However, as with Jupiter, Saturn rotates on its axis faster than Earth, so a day on Saturn is only about 10.7 hours long.
- Discovery of Saturn: Saturn is the furthest planet from the Earth that was discovered without the use of technology. Because it can be seen with the naked eye, it has been observed since ancient times.
However, in 1610, with telescopic technology at his disposal, Galileo Galilei is also credited with being the first person to detail Saturn and discover its rings.
Composition Of Saturn
Saturn is also composed of mostly hydrogen and helium. It has a dense, rocky, and metallic core surrounded by liquid hydrogen, which is formed by the extreme pressures deeper within Saturn. The outer layers of the planet are gaseous hydrogen and helium, with small amounts of other elements, which create the banded appearance of Saturn’s surface.
Saturn’s Rings
Saturn’s rings are phenomenal. They look solid in the images we are accustomed to seeing, but they are actually composed of rock and ice, ranging from the size of dust particles to the size of houses, and a few even larger than that.
Saturn has seven rings. Moving from the outer rings inward, these are E ring, G ring, F ring, A ring, B ring, C ring, and D ring. This may seem like a nonsensical naming system, but the rings were named alphabetically according to when they were discovered. Between A ring and B ring, there is a gap known as the Cassini Division, which extends 2,920 miles.
The rings are only approximately 30 feet thick, a tiny measurement in astronomical terms. However, the whole ring system is 262,670 miles wide. That’s over 3.5 times wider than Saturn itself!
Saturn’s Moons
Saturn has even more moons than Jupiter! There are 53 officially named moons and another 29 still waiting to be confirmed and named.
| Saturn’s Confirmed And Named Moons | |||
| Aegaeon | Aegir | Albiorix | Anthe |
| Atlas | Bebhionn | Bergelmir | Bestla |
| Calypso | Daphnis | Dione | Enceladus |
| Epimetheus | Erriapus | Farbauti | Fenrir |
| Fornjot | Greip | Hati | Helene |
| Hyperion | Hyrrokkin | Iapetus | Ijiraq |
| Janus | Jarnsaxa | Kari | Kiviuq |
| Loge | Methone | Mimas | Mundilfari |
| Narvi | Paaliaq | Pallene | Pan |
| Pandora | Phoebe | Polydeuces | Prometheus |
| Rhea | Siarnaq | Skathi | Skoll |
| Surtur | Suttungr | Tarqeq | Tarvos |
| Telesto | Tethys | Thrymr | Titan |
| Ymir |
If you’re looking for a good baby name, look no further! Just kidding. But with all of these moons, only two are of significant scientific relevance: Enceladus and Titan.
While we can speculate at frozen, subterranean oceans on other astrological objects, you can see these clearly on the surface of Enceladus. From samples collected by spacecraft, astronomers believe that Enceladus may just have most of the chemical requirements to support life. Enceladus also holds the title of being the “most reflective surface in the solar system”.
Titan is the largest of Saturn’s moons, but that’s not what makes it intriguing to scientists. Titan is under the microscope because of its similarities to Earth and what this could mean. Titan has a substantial atmosphere and liquid rivers, lakes, and seas on its surface. Is there life on Titan? Or could there be?
3. Uranus
How Did Uranus Get Its Name?
Uranus is the Latinized name for the ancient Greek god Ouranos, the god of the sky, possibly because of the planet’s blue color. This was in keeping with the tradition of naming our solar system’s planets after mythical gods. But Uranus was almost not called Uranus.
The man who discovered this planet wanted to name it after the reigning monarch of the time, King George III. If he had his way, Uranus would be called Georgium Sidus. Eventually, however, Johann Bode came up with the name Uranus.
Features And Facts About Uranus
- Size: Uranus has a diameter of 31,518.4 miles, making it the third-largest planet in our solar system and almost 4 times the width of Earth. Additionally, it is more than 14.5 times greater in mass than the Earth.
- Distance from the sun and surface temperature: Uranus is 19.8 times further from the sun than the Earth is and the average temperature on Uranus is -353°F. Thus, it will not surprise you to learn that Uranus is also known as an Ice Giant.
- Orbit and rotation: As the planets get further from the sun, a year cycle takes longer. A Uranian year is 84 times longer than an Earth year.
The rotation of Uranus is slower than that of Jupiter and Saturn, but it is still faster than Earth. A single day on Uranus only lasts about 17 hours and 14 minutes. Uranus’s rotation is interesting for two reasons.
The first is that it rotates sideways with a spin axis of almost 90 degrees to the planet’s equator. This means that there are extreme seasonal changes. According to NASA, “For nearly a quarter of each Uranian year, the sun shines directly over each pole, plunging the other half of the planet into a 21-[Earth]year-long, dark winter”.
The other notable rotational feature of Uranus is that it spins in the opposite direction to most other planets.
These two factors indicate that something massive must have collided with Uranus at some point in its life.
- Discovery of Uranus: Uranus was discovered in 1781 by William Herschel, and it was the first planet to be discovered with a telescope (invented in the 1600s).
Composition Of Uranus
80+% of Uranus is made up of water, methane, and ammonia, which NASA paradoxically describes as being icy materials that form a hot, dense fluid. Its core is small and rocky.
The absorption of red visible light by the methane gas of Uranus is what gives it its green-blue color.
Uranus’s Rings
Uranus has two ring systems. The inner ring system has nine dark gray and narrow rings, and the outer ring system has one red ring and one blue one. The blue ring called Mu, and the red ring is called Nu. Then the inner rings names’ (from outermost to innermost) are Epsilon, Lambda, Delta, Gamma, Eta, Beta, Alpha, 4, 5, 6, and Zeta.
Uranus’s Moons
Uranus has 27 moons, and they are called the literary moons because they were all named after literary characters, specifically those featured in the works of William Shakespeare and Alexander Pope.
| Uranus’s Confirmed And Named Moons | |||
| Ariel | Belinda | Bianca | Caliban |
| Cordelia | Cressida | Cupid | Desdemona |
| Ferdinand | Francisco | Juliet | Mab |
| Margaret | Miranda | Oberon | Ophelia |
| Perdita | Portia | Prospero | Puck |
| Rosalind | Setebos | Stephano | Sycorax |
| Titania | Trinculo | Umbriel |
4. Neptune
How Did Neptune Get Its Name?
Due to its vivid blue color, Neptune is named after the ancient Roman god of the sea.
Features And Facts About Neptune
- Size: The diameter of Neptune is 30,598.8 miles, making it only 919.6 miles smaller than Uranus. However, at 17 times the Earth’s mass, Neptune is denser than Uranus.
- Distance from the sun and surface temperature: Neptune is the Gas Giant furthest from the sun at 30 times further from the sun than the Earth. It has an average temperature of -392°F, making it only slightly colder than Uranus. Its cold temperature also earns Neptune the title of Ice Giant.
- Orbit and rotation: In the time it takes for Neptune to complete one orbit around the sun, Earth completes 165 orbits! A day on Neptune lasts about 16 Earth hours because Neptune rotates faster on its axis than Earth does.
- Discovery of Neptune: Neptune was the first planet whose existence was predicted using mathematics. Using a telescope, the discovery was then confirmed in 1846.
Composition Of Neptune
Neptune is almost identical in composition to Uranus, but it is the densest of all the Gas Giants.
Neptune’s Rings
Neptune has five primary rings. From outermost to innermost, these rings are Adams, Arago, Lassell, Leverrier, and Galle.
In addition to these rings, Neptune has four arcs: Liberté, Egalité, Fraternité, and Courage. These arcs are clumps of dust, and scientists believe that they are held in orbit by the gravitational field of Galatea, one of Neptune’s moons.
Neptune’s Moons
Neptune has only 14 moons, which were all named after lesser sea gods and nymphs to carry on the Neptune theme.
| Neptune’s Confirmed And Named Moons | |||
| Despina | Galatea | Halimede | Laomedeia |
| Larissa | Naiad | Nereid | Neso |
| Proteus | Psamanthe | Sao | Thalassa |
| Triton |
5. 51 Pegasi b
51 Pegasi b is the name given to the first exoplanet discovered to be orbiting a sun-like star. It was discovered in 1995, and it orbits its star much closer than any of our solar system’s gas planets do. In fact, it is so close to its parent star that it only takes 4.2 days to complete one orbit.
51 Pegasi b has a radius approximately 1.27 times that of Jupiter and a mass of approximately 0.46 times that of Jupiter.
6. KELT-9 b
KELT-9 b is another gaseous exoplanet, and it was only discovered in 2017. It, too, orbits its parent star closely, taking only 1.5 days to complete an orbit.
KELT-9 b has a radius approximately 1.891 times that of Jupiter and a mass of approximately 2.88 times that of Jupiter.
7. Kepler-7 b
Kepler-7 b is a Gas Giant exoplanet that was discovered in 2009. It completes one orbit around its parent star in 4.9 days.
Kepler-7 b has a radius approximately 1.622 times that of Jupiter and a mass of approximately 0.441 times that of Jupiter.
Conclusion
There are four Gas Giant planets in our solar system: Jupiter, Saturn, Uranus, and Neptune. We know quite a bit about these planets, although there are still plenty of mysteries surrounding them. Then there are also gas planets outside of our solar system. In the last few decades, these exoplanets have been discovered, but little is known about them thus far.
