Learn About The Planets

Solar System - SUN

The Sun is the most prominent feature in our solar system. It is the largest object and contains approximately 98% of the total solar system mass. One hundred and nine Earths would be required to fit across the Sun's disk, and its interior could hold over 1.3 million Earths. The Sun's outer visible layer is called the photosphere and has a temperature of 6,000°C (11,000°F). This layer has a mottled appearance due to the turbulent eruptions of energy at the surface.

Solar System - SUN

The Sun is a star - it is not a planet. Our Sun is just like the stars we see in the night sky. The Sun is also the only star we see during the daytime. The Sun is about 75% hydrogen and 25% helium. This changes slowly over time as the Sun converts hydrogen to helium in its core (center). Beside, the Sun's energy is produced by nuclear fusion reactions. It generates 386 billion megawatts of energy. The sun Contains darkspots that are known as sunspots.

Mercury

Mercury

Mercury - the closest planet to the Sun, takes only 88 days to orbit the Sun.

Size - Mercury is about 3,032 miles (4,880 kilometers) across. That makes it the smallest planet in the solar system. In fact, Mercury is just a little larger than Earth's Moon.

Distance from the Sun - Mercury is the closest planet to our star, with its average distance from the Sun being 36 million miles (58 million km).

Orbit around the Sun - Because Mercury is so close to the Sun, it has the smallest orbit of all the planets. Mercury's year (the time it takes to orbit the Sun one time) is 88 Earth days long.

Rotation - Although Mercury goes around the Sun quickly, it spins very slowly on its axis — about 59 Earth days for every rotation.

Surface - Scientists believe that Mercury has a thin, rocky crust, with a large metallic core, probably made of iron, at its center. Mercury is covered with craters and has ice at its poles.

Atmosphere - Mercury has an extremely thin atmosphere of helium and hydrogen captured from the solar wind.

Temperature - On Mercury, you would either freeze or roast. The highest surface temperature is 870° F (466° C), while the lowest temperature is –300 °F (–184 °C).

Escape velocity -  To escape Mercury's gravity, you have to travel 9,600 miles (15,500 km) per hour, compared to 25,000 miles (40,200 km) per hour necessary to escape Earth's gravity.

 

Venus
The surface of Venus, the brightest object in the sky after the Sun and Moon, is covered with craters, mountains, volcanos, and lava plains.

After the Sun and Moon, Venus is the brightest object in the sky. Because its thick clouds reflect most of the light Venus gets from the Sun, the planet looks like a very bright star in the morning (just before sunrise) or evening (just after sunset) sky.

Sometimes called Earth's sister planet, Venus is slightly smaller than Earth. It's also our closest neighbor, approaching within 25 million miles (40 million km).

Venus

In Roman mythology, Venus was identified with the goddess of love and beauty, Aphrodite. To the ancient Mayans, Venus was the patron planet of warfare called Kukulcan, or the feathered serpent.

Size - Venus is about 7,521 miles (12,104 kilometers) in diameter.

Distance from the Sun - The second planet from our star has an average distance from the Sun of 67 million miles (108 million km).

Orbit around the Sun - It takes 225 Earth days for Venus to go around the Sun one time.

Rotation - Venus spins on its axis once every 243 Earth days, but it spins in the opposite direction of Earth. On Venus, the Sun rises in the west and sets in the east.

Surface - The surface of Venus is covered with craters, mountains, volcanoes, and lava plains. Maxwell Montes is the highest point on Venus. It is more than 7 miles (11 km) high.

Atmosphere - Possessing sulfuric acid clouds, the atmosphere of Venus is mostly carbon dioxide (96 percent), nitrogen (3.5 percent), and carbon monoxide, argon, sulfur dioxide, and water vapor (all less than 1 percent). The atmosphere is so thick and heavy that it bends light, making the ground appear to curve upward in all directions. The planet's atmosphere is ninety times heavier than Earth's.

Temperature - Venus's surface temperature can get close to 900° F (482° C), hot enough to melt lead. This makes Venus the hottest place in the solar system after the Sun. Escape velocity -  To escape Venus's gravity, you have to travel 23,300 miles (37,500 km) per hour, compared to 25,000 miles (40,200 km) per hour necessary to escape Earth's gravity.

Earth

Earth is the third planet from the Sun and takes 23 hours, 56 minutes to spin on its axis one time.

Earth

Size - Earth has a diameter of 7,926 miles (12,756 kilometers).

Distance from the Sun - Earth is the third planet from the Sun, which is about 93 million miles (150 million km) away.

Orbit around the Sun - Earth goes around the Sun in 365 and 1/4 days. Every 4 years, the extra quarters add up to one whole day and we add a day to the end of February, creating a leap year.

Rotation - It takes only 23 hours, 56 minutes (1 day) for Earth to spin on its axis one time relative to the stars.

Surface - From space, Earth looks like the blue water world it is. About 70 percent of Earth's surface is covered with water, and 97 percent of all that water is in the salty oceans. Only 3 percent of Earth's water is freshwater — the water we drink. Earth is covered with mountains, volcanoes, lakes, rivers, and oceans. Most of the surface material is made of rocks — high in silica, iron, and magnesium.

Atmosphere - Earth's atmosphere is a mixture of gasses that becomes thinner as we move away from the planet toward space. Most of the atmosphere is nitrogen (78 percent), oxygen (21 percent), argon, and other gases (1 percent). Some of the oxygen in Earth's atmosphere has changed over time to form ozone. Earth's high ozone layer filters out the Sun's harmful ultraviolet rays, protecting the living beings on the surface. Ozone at ground level, however is an irritant to eyes, nose, and throats. Temperature - Earth's average temperature is 60° F (15.5° C). Escape velocity - To escape Earth's gravity, you have to travel 25,000 miles (40,200 km) per hour.

Mars 
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance.

Mars

Size - Mars is about 4,212 miles (6,779 kilometers) in diameter.

Distance from the Sun - Mars is the fourth planet from the Sun and orbits roughly 142 million miles (229 million km) away.

Orbit around the Sun - It takes 687 Earth days for the Red Planet to go around the Sun one time. Rotation - Mars spins on its axis at about the same speed as Earth does. It takes 24 hours and 37 minutes (about 1 Earth day) for Mars to rotate one time. Atmosphere - The martian atmosphere is very thin and made of carbon dioxide (95 percent), nitrogen (3 percent), argon and other gases (1 percent). Temperature - The lowest surface temperature on Mars is –190° F (–123° C), while the hottest temperature is 90° F (32° C).

Surface - There are lots of dry channels on Mars, and they look like Earth's river channels. Most scientists believe water once flowed on the martian surface, but new studies suggest there still may be water in some places at and under the surface. Mars has the largest canyon (Valles Marineris), and the highest volcano (Olympus Mons) in the solar system. If Valles Marineris were on Earth, it would span the United States, from New York on the East Coast to California on the West Coast. The canyon is about 1,300 miles (2,100 km) long, 300 miles (500 km) wide, and about 5 miles (8 km) deep. Olympus Mons is about three times higher than Mount Everest. It rises above the Martian surface 14 miles (22 km). This giant volcano's base is the size of the state of Missouri. The planet's reddish color is caused by rust (iron oxide) in the soil. The polar ice caps on Mars are made of frozen carbon dioxide, or dry ice, plus a seasonal coating of water ice.

Escape velocity - To escape the gravity of Mars, you have to travel 11,200 miles (18,000 km) per hour, compared to 25,000 miles (40,200 km) per hour necessary to escape Earth's gravity.

Jupiter 

Jupiter

Jupiter is the largest planet in our solar system, with a diameter of 89,000 miles. Jupiter has a "pizza moon." Sulfur-spewing volcanoes cover the surface of Io. At different temperatures, sulfur appears in different colors, making Io look like a giant pizza.

Size - Eleven Earths would fit side by side across the face of Jupiter. It is the biggest planet in the solar system, and it has a diameter of 89,000 miles (143,000 kilometers).

Distance from the Sun - Jupiter is the fifth planet from the Sun. Its orbit is about 483 million miles (777 million km) away from the Sun. That's five times farther than Earth's orbit.

Orbit around the Sun - It takes Jupiter 12 Earth years to go around the Sun once. So on your twelfth birthday, Jupiter is in roughly the same place of the solar system as it was on the day you were born.

Rotation - Although Jupiter takes a long time to go around the Sun, it takes only 10 hours to spin on its axis one time. That's less than half the time it takes Earth to spin once.

Surface - Jupiter does not have solid surface — its gaseous material becomes denser with depth.

Atmosphere - Jupiter's atmosphere is made mostly of hydrogen (86 percent) and helium (14 percent). The colorful cloud bands we see are actually cloud layers. Darker clouds tend to be deeper in Jupiter's atmosphere, while the lighter or white clouds are higher. The atmosphere also has giant lightning storms in its upper clouds.

Temperature - The average temperature at the top of Jupiter's clouds is –244° F (–153° C). Escape velocity - To escape Jupiter's gravity, you have to travel 133,100 miles (214,200 km) per hour, compared to 25,000 miles (40,200 km) per hour necessary to escape Earth's gravity.

Saturn

Saturn

Saturn, the sixth planet from the Sun, has a ring system made up of ice and rock particles, some as big as a minivan. Saturn is also called the "ringed planet." Although Jupiter, Uranus, and Neptune also have ring systems, Saturn's is the largest.

Size - Saturn would hold 9 1/2 Earths spread across its face. It is the second-largest planet in the solar system and has a diameter of 74,900 miles (120,500 kilometers).

Distance from the Sun - Saturn is the sixth planet from the Sun, with an orbit roughly 888 million miles (1.43 billion km) away.

Orbit around the Sun - Saturn journeys 29.4 Earth years to go around the Sun once.

Rotation - It takes Saturn only 11 hours to spin on its axis one time.

Surface - Saturn does not have solid surface.

Atmosphere - The atmosphere of this ringed planet is like Jupiter's atmosphere. Saturn holds mostly hydrogen (97 percent) and helium (3 percent). Saturn also has beautiful bands like Jupiter, but these colorful features are hidden by haze and smog that make up the planet's high atmosphere.

Temperature - The average temperature on Saturn is –300° F (–184° C). Escape velocity - To escape Saturn's gravity, you need to travel 79,400 miles (127,800 km) per hour, compared to 25,000 miles (40,200 km) per hour necessary to escape Earth's gravity.

 

Uranus

Uranus, the third-largest planet in the solar system, has an average temperature of –350° F and does not have a solid surface. Uranus is the planet tipped on its side. Uranus spins more like a barrel on its side than a top. This strange tilt may be the result of a collision with another body that tipped Uranus on its side.

In mythology, Uranus was the father of Saturn and grandfather of Jupiter.

Uranus Size - About 4 Earths would fit side by side across the face of Uranus. Its diameter is 31,800 miles (51,100 kilometers), making it the third-largest planet in the solar system.    Distance from the Sun - The seventh planet from the Sun, Uranus orbits at a distance of about 1.8 billion miles (2.9 billion km), more than 19 times farther than Earth's orbit. Orbit around the Sun - Uranus goes around the Sun once every 84 Earth years. Rotation - Uranus spins on its axis one time every 17 hours. Surface - Uranus does not have solid surface. Atmosphere - The atmosphere of Uranus holds hydrogen (83 percent), helium (15 percent), and methane (2 percent). Methane is what gives Uranus its blue-green color.

Temperature - Uranus is very cold — its average temperature is –350° F (–210° C). Escape velocity - To escape the gravity of Uranus, you need to travel 47,600 miles (76,600 km) per hour, compared to 25,000 miles (40,200 km) per hour necessary to escape Earth's gravity.

Neptune

Neptune has 13 moons, the two largest are Triton and Nereid. Triton is made of rock and ice. Its surface is rich in water ice, dry ice, frozen carbon monoxide, methane, and nitrogen. Triton has cold geysers that spit nitrogen instead of the hot water that geysers on Earth release. Neptune was only the god of water, but later on this was extended to include the sea when he became associated with the Greek god Poseidon.

Neptune

Size - Neptune is slightly smaller than Uranus and has a diameter of 31,000 miles (50,000 kilometers), so about 4 Earths would fit across its face. Distance from the Sun - Neptune is the eighth planet from the Sun. It orbits at an average distance of 2.8 billion miles (4.5 billion km), thirty times farther than Earth. Orbit around the Sun - It takes 165 Earth years for Neptune to go around the Sun one time. Rotation - It takes Neptune only 16 Earth hours for it to spin on its axis once.  Surface - Like the other gas-giant planets, Neptune's "surface" is the top of its deep atmosphere. This contains hydrogen (79 percent), helium (18 percent), and methane (3 percent), which gives the planet its blue color. Neptune's atmosphere has a striped pattern like both Jupiter's and Saturn's.

Temperature - The average temperature at Neptune is –370° F (–220° C). Escape velocity - To escape Neptune's gravity, you need to travel 52,600 miles (84,700 km) per hour, compared to 25,000 miles (40,200 km) per hour necessary to escape Earth's gravity.

Pluto

Pluto

Pluto, reclassified as a dwarf planet in 2006, is located nearly 40 times as far from the Sun as Earth.

In July 1978, James Christy discovered Pluto's moon, Charon. This moon is about half as big as Pluto itself. In May 2005, astronomers used the Hubble Space Telescope to hunt for undiscovered moons around Pluto. They found two moons,provisionally known as S/2005 P1 and S/2005 P2.

Pluto was thought to be the god to whom all men must eventually go. Romans believed him to be the god of the underworld. In Greek mythology, he is known as Hades.

Size - With a diameter of only 1,485 miles (2,390 kilometers), Pluto was the smallest planet in the solar system. In 2006, the International Astornomical Union reclassified Pluto as a dwarf planet. Distance from the Sun - Pluto was the ninth planet from the Sun. It orbits our star at a distance of 3.6 billion miles (5.9 billion km), nearly forty times as far from the Sun as Earth. Orbit around the Sun - It takes Pluto 248 Earth years to go around the Sun one time. Rotation - Pluto spins on its axis once every 6 Earth days. Surface - Pluto's surface has dark markings and probably is made of methane and nitrogen ice on top of a rock and water ice mixture. Atmosphere - Pluto has a very thin atmosphere of nitrogen and methane.

Temperature - The average temperature on Pluto is –390° F (–235° C). Escape velocity - To escape Pluto's gravity, you need to travel 2,500 miles (4,000 km) per hour, compared to 25,000 miles (40,200 km) per hour necessary to escape Earth's gravity.