Gas Giant Planets
GAS GIANT PLANET FACTS
The home of interesting Gas Giant planet facts for kids and adults.
What is a Gas Giant planet?
The first thing to understand about terrestrial planets is that they are mostly made of rock. Earth of course is the 'original' terrestrial planet, that is it was the first planet to be given this designation. When astronomers were first starting to learn about the types of planets in our solar system, they began to extend the designation to our nearest rocky neighbours.
Gas giant planets in our solar system
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Mercury
More facts about MercuryMercury is wrinkled due to its Iron core. This cools and contracts causing Lobate scarps (its wrinkles)
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10 Facts about gas giant planets
1. Four planets closest to the sun
Our solar system contains 8 planets, 4 of which are classified as gas giants and 4 are what is known as terrestrial planets. The four terrestrial planets in our solar systems are Earth, Mars, Venus and Mercury.
Did you know?
The terrestrial planets are also known as the ‘inner planets’.
2. What's in a name?
The word terrestrial is derived from the Latin Terra, which means Earth. Terrestrial planets are so-called because of their composition and their similarity to Earth. Conditions on the two planets closest to the Sun, Venus and Mercury, are far too harsh to host any kind of life.
Did you know?
Terrestrial planets are those defined as having solid surfaces
3. Mercury has been well known for a long time
It is thought that civilizations as far back as 5,000 years ago were aware of Mercury. Mercury takes its name from the Roman messenger god. Mercury was known in Roman mythology for moving quickly, and the planet was given his name because it orbits the Sun faster than other planets.
Did you know?
Mercury is the smallest of the planets in our solar system.
4. Earth is the only planet home to life
As far as we can tell, the planet Earth is the only planet, terrestrial or otherwise, that supports life. Our little part of the solar system was formed approximately 4.54 billion years ago
Did you know?
It is thought that Mars once supported life
5. Mars’ core is very dense
The core of the planet Mars, the second smallest terrestrial planet, is very dense indeed and is made of iron, sulphur and nickel. Mars' crust is made up of aluminium, iron, potassium, magnesium and calcium. Thanks to various Mars Rovers, we can see how smooth the northern hemisphere is.
Did you know?
Mars is home to the largest crater in our solar system, its name is Valles Marineris.
6. Earth is the only planet that has water on its surface
Earth is the only planet known to have water on its surface. Other planets do have water, but this below surface. Our little home is a very watery place, and around 71 per cent of the planet's surface is water. 96 per cent of all water on Earth is contained within its oceans.
Did you know?
Some of Earth’s water may well have come from comets.
7. The Hubble Space Telescope cannot ‘see’ Mercury or Venus
The Hubble Space Telescope is an advanced piece of equipment, but it does have limitations. One of these is that its instruments are very sensitive. Because of this, it cannot observe the Sun and in turn, cannot observe Mercury or Venus because they are too close to the Sun.
Did you know?
Did you know: The Hubble orbits the Earth at a speed of 17,000 miles per hour.
8. Earth is the largest terrestrial planet
Of all of the terrestrial planets or the 'inner' planets, Earth is the largest with a diameter of 7,917.5 miles. The smallest is Mercury with a diameter of 3,030 miles, and it takes just 3 of our months for it to go around the Sun once.
Did you know?
After Mars, the Earth is the furthest terrestrial planet from the Sun with a distance of 149.6 million kilometres.
9. Mercury is closest to the Sun, but not the hottest
Although Mercury is the closest planet to the Sun, Venus is the hottest terrestrial planet. If that doesn’t make sense, it’s because of the different atmospheres of the two planets. The atmosphere of Mercury is very light, whereas that of Venus is very thick making the levels of carbon dioxide very high, raising the temperature.
Did you know?
That while Venus is the hottest planet, Uranus is the coldest
10. Not all terrestrial planets have moons
Earth has just one moon, simply called the Moon, while Mars has two moons. Mercury and Venus however do not have any moons at all. Mercury used to have a moon until it was taken by the Sun’s gravitational pull – it is thought that Venus once had a moon too and this was also taken by the Sun.
Did you know?
The two moons of Mars are named Phobos and Deimos, after the Greek mythological characters Phobos (fear) and Deimos (dread).