What is a planet? A planet is a celestial body that orbits a star (like the Sun), has sufficient mass to assume a nearly round shape under its own gravity, and has cleared its orbital path of other debris. Planets vary in size, composition, and distance from their stars, and they can be rocky or gaseous. Earth, for example, is a terrestrial (rocky) planet, while Jupiter is a gas giant.
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Image Credit: NASA
10 facts about planets:
10 facts about planets:
There are eight planets in our solar system: The eight planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto used to be considered the ninth planet but is now classified as a dwarf planet.
The largest planet is Jupiter: Jupiter is about 11 times the diameter of Earth and is made mostly of hydrogen and helium. It has a massive storm called the Great Red Spot that has been raging for at least 400 years.
Earth is the only known planet with life: Earth has the right conditions—liquid water, an atmosphere, and a moderate temperature—needed to support life.
Venus is the hottest planet: Venus has a thick atmosphere made mostly of carbon dioxide, which traps heat through the greenhouse effect, making it the hottest planet in our solar system, even hotter than Mercury, the closest planet to the Sun.
Mars has the tallest volcano: Mars is home to Olympus Mons, the largest volcano in the solar system. It stands at about 13.6 miles (22 km) high, nearly three times the height of Mount Everest.
Saturn's rings are made of ice and rock: Saturn’s famous rings are composed mostly of water ice, with some rock and dust. They are believed to be the remnants of moons or comets that were torn apart by Saturn's gravity.
Neptune has the strongest winds: Neptune's winds can reach speeds of up to 1,500 miles per hour (2,400 km/h), which is faster than the speed of sound on Earth.
Uranus rotates on its side: Unlike most planets, Uranus has an extreme axial tilt of about 98 degrees, meaning it essentially rolls around the Sun on its side.
Mercury has extreme temperature swings: Because it has almost no atmosphere, Mercury experiences drastic temperature differences, ranging from 800°F (427°C) during the day to -330°F (-201°C) at night.
There are exoplanets outside our solar system: Scientists have discovered thousands of exoplanets (planets outside our solar system), some of which may have conditions similar to Earth and could potentially support life.
Bonus Fact about a weird planet:
Bonus Fact about a weird planet:
One of the weirdest planets discovered is HD 189733b. It is a hot Jupiter exoplanet, located about 63 light-years away from Earth. This planet is incredibly hostile: it has rains of glass that fall sideways due to wind speeds of up to 5,400 miles per hour (8,700 km/h). The atmosphere is filled with toxic gases, and temperatures can reach over 1,000°C (1,832°F). It's a truly extreme world!
Click on any of the names below to learn more about each of the planets in our own solar system.
Mercury | Venus | Earth | Mars | Jupiter | Saturn | Uranus | Neptune | Dwarf Planet Pluto
A dwarf planet is a celestial body that orbits the Sun, has enough mass to be nearly round in shape, but has not cleared its orbital path of other debris.
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