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Astronomy

Explore the Solar System, planets, stars, and space science encyclopedia entries.

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True-color view of Pluto from New Horizons
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Pluto: The Famous Dwarf Planet

Pluto is the famous dwarf planet: icy mountains, nitrogen ice, large moon Charon, and discoveries from NASA’s New Horizons.

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Voyager 2 image of deep blue Neptune
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Neptune: The Farthest Planet from the Sun

Neptune is the farthest major planet: a deep-blue ice giant with extreme winds, faint rings, and the retrograde moon Triton.

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Voyager image of pale cyan planet Uranus
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Uranus: The Sideways Ice Giant

Uranus is the sideways ice giant: extreme tilt, long seasons, methane-blue color, dark rings, and a rarely visited outer world.

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Saturn and rings during equinox Cassini view
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Saturn: The Ringed Giant of the Solar System

Saturn is the ringed gas giant: bright icy rings, fast spin, low density, and remarkable moons Titan and Enceladus.

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Jupiter with cloud belts and Great Red Spot
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Jupiter: The Largest Planet in the Solar System

Jupiter is the largest planet: a hydrogen-helium gas giant with a 10-hour day, the Great Red Spot, and moons including Europa.

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True-color image of Mars
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Mars: The Red Planet Explained

Mars is the Red Planet: thin CO2 air, giant volcanoes, deep canyons, polar ice, two moons, and strong evidence of ancient water.

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The Blue Marble photograph of Earth from Apollo 17
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Earth: Our Living Home Planet

Earth is the third planet and only known living world: oceans, oxygen-rich air, magnetic field, plate tectonics, and one large Moon.

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Real-color image of Venus cloud cover
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Venus: Earth’s Hot Twin Planet

Venus is Earth’s size twin and the hottest planet: thick CO2 air, acid clouds, crushing pressure, and a slow backward spin.

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True-color view of planet Mercury showing a gray cratered globe
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Mercury: The Closest Planet to the Sun

Mercury is the closest planet to the Sun: extreme heat and cold, a huge iron core, polar ice, and a day longer than its year.

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