Outer Planets

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Gas Giant Noun

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[gas jai-uhnt]

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Gas Giant

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A large planet composed mainly of gases, like hydrogen and helium, with a relatively small rocky core.

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Example: This image identifies the four gas giants in our solar system: Jupiter, Saturn, Uranus, and Neptune, which are all outer planets.

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Mass Noun

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[mas]

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Mass

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A measure of the amount of matter in an object, representing a fundamental property distinct from its weight.

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Example: This diagram shows a triple-beam balance measuring the mass of a cube, which is the amount of matter that makes up an object.

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Gravitational Force Noun

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[grav-i-tey-shuh-nl fors]

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Gravitational Force

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The fundamental force of attraction that exists between all objects with mass or energy in the universe.

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Example: This image shows that an object, like a thrown ball, follows a curved path back to the ground because of the constant downward pull of Earth's gravitational force.

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Atmosphere Noun

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[at-muh-sfeer]

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Atmosphere

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The envelope of gases surrounding a planet or other celestial body, held in place by its gravitational pull.

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Example: This diagram shows the layers of an atmosphere, the blanket of gases surrounding a planet. However, it illustrates Earth's specific layers, not those of an outer planet.

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Rings Noun

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[ringz]

Back

Rings

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A thin disc of small rock and ice particles orbiting a planet in a flat, circular formation.

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Example: This image shows the planet Saturn, an outer planet famous for its large and complex system of rings made of countless ice and rock particles.

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Diameter Noun

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[dai-am-i-ter]

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Diameter

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A straight line passing from side to side through the center of a celestial body, measuring its size.

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Example: This diagram shows the diameter of a circle, which is a straight line passing through the center and connecting two points on its edge.

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Hydrogen Noun

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[hai-druh-juhn]

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Hydrogen

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The lightest and most abundant chemical element, which is a primary gaseous component of gas giant planets.

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Example: This diagram shows a hydrogen atom, the simplest element, with one proton in the nucleus and one electron orbiting it.

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Helium Noun

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[hee-lee-uhm]

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Helium

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The second-lightest chemical element and a primary component of the atmospheres of the gas giant planets.

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Example: This diagram shows a Helium atom, which has an atomic number of 2. It has two electrons orbiting a nucleus, making it a stable noble gas.

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Core Noun

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[kor]

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Core

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The central, innermost part of a planet, often composed of dense materials like rock and metal under extreme pressure.

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Example: This cutaway diagram shows the layers of Earth, including the liquid outer core and the solid inner core, which are at the planet's center.

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Methane Noun

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[meth-eyn]

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Methane

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A chemical compound gas that absorbs red light, giving planets like Uranus and Neptune their distinct blue color.

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Example: This image shows a model of a methane molecule, which has one carbon atom (center) and four hydrogen atoms, a key gas in outer planet atmospheres.