Neptune's Atmosphere: Lesson for Kids

Instructor: Corrie Boone

Corrie holds master's in elementary education, taught elementary ESL in the public schools for 5 years, and recently was teaching EFL abroad.

Neptune, the eighth and last planet in our solar system, is brightly blue, is called a gas giant and an ice giant, and experiences very powerful storms! Keep reading to find out what it is about Neptune's atmosphere that causes all these things.

All About Neptune

Neptune is the eighth and last planet in our solar system, but what do you know about it? Neptune appears very blue, but why? What about the atmosphere of Neptune? (Hint: It's very different from Earth's.) Why is Neptune called a gas giant? Keep reading to learn all about Neptune.

The Gas Giants

An atmosphere is the layers of gas surrounding a planet. Every planet has a unique atmosphere, making it a little - or a lot different - from the others.

Neptune belongs to a group of four planets in our solar system called the gas giants: Jupiter, Saturn, Uranus, and Neptune. They're called this because they are very large and made of gas. Earth has a solid surface we can stand on; Neptune is made of gas and doesn't have a solid surface. If you tried to stand on Neptune, you would sink down through the layers of gas until you hit the solid core deep in the center.

Jupiter and Saturn are both enormous planets, while Uranus and Neptune are relatively smaller. However, while Neptune is small compared to the larger gas giants, it's gigantic when compared to Earth - about four times larger, in fact! This also makes it the fourth largest planet in the whole solar system.

Size of Neptune vs. size of Earth
Neptune compared to Earth

The Blue Planet

As we said earlier, Neptune's atmosphere is made of gases. To be specific, it's made of hydrogen and helium, with a little bit of methane. The methane is what gives Neptune its blue color. Methane absorbs red light and reflects blue light, causing Neptune to appear brightly blue.

Interestingly, Uranus has a similar amount of methane in its atmosphere, but appears more blue-green than Neptune. Scientists aren't exactly sure why, but some think there's an unknown substance in Neptune's atmosphere causing this.

Neptune is bright blue; Uranus is blue-green
Neptune vs. Uranus

Layers of the Atmosphere

Neptune's atmosphere is composed of four layers. Starting with the innermost layers and moving out towards space, are two main layers: the troposphere and the stratosphere. In the troposphere, the first layer, the temperature decreases as you move outwards. However, in the stratosphere, the second layer, the opposite is true: as you move outwards, the temperature increases. It's believed this is because the inside of the planet is very hot and heats Neptune more than the sun.

Above the stratosphere are two smaller layers: the thermosphere and the exosphere. Neptune's thermosphere confuses scientists because the temperature is extremely high (890 F) even though it's very far from the sun. The exosphere is the last, very thin layer; this is where the planet's atmosphere merges with space.

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