Meet the planets.

Meet the Planets
This chart is filled with fun and unusual facts about our solar system.
study the chart to complete the exercise that follows.

Body      Fast Fact

Sun       The sun is not a planet. It is a star, just
          one out of hundreds of billions in our
          galaxy, the Milky Way. In ancient times,
          people believed planets revolved
          around Earth. But that changed when
          16th-century Polish astronomer
          Nicolaus Copernicus proposed that the
          sun was the center of the solar system.

Mercury   Mercury zips at an average of 29 miles
          (47 kilometers) per second to orbit the
          sun in 88 days--faster than any other
          planet in the solar system. It was
          named after the Roman messenger god
          who was said to have wings on his
          heels to carry him swiftly from Earth to
          the heavens.

Venus     Named after the Roman goddess of
          love and beauty, Venus is the second-brightest
          object in the night sky. Just
          dimmer than Earth's moon, the planet
          is often called Morning or Evening Star.
          It is also referred to as Earth's "sister
          planet" because they are similar in size.

Earth     Earth is the only planet not named after
          a Greek or Roman god. It's also the
          only planet known to have life, oceans
          of water, and plenty of oxygen in its
          atmosphere, or the layers of gas that
          surround a planet.

Moon      The moon is Earth's only natural satellite.
          The "face" on the moon is large, ancient
          craters filled in with lava that began as
          magma inside the moon.

Mars      Mars is the Roman god of war. The
          planet may have been given this name
          because of its fiery color. Mars gets its
          red coloring from iron oxide (rust)-
          rich soil. It is often referred to as the
          Red Planet.

Jupiter   Jupiter, the largest planet in the solar
          system, was named after the Roman
          ruler of the gods. It's 318 times more
          massive than Earth. In fact, it is more
          massive than all the other planets in
          the solar system combined.

Saturn    Named after the Roman god of agriculture,
          Saturn was the most-distant
          planet known to humans before the
          invention of the telescope. Because
          Saturn features wide, thin rings of ice
          and rock particles, it's often called the
          "ringed planet."

Uranus    Uranus, the first planet discovered
          with a telescope, was spotted in 1781
          by William Hershel of Bath, England.
          First named "the Georgian Planet" in
          honor of King George III, it was later
          renamed Uranus after the Greek god
          of the heavens.

Neptune   Neptune was named after the Roman
          god of the sea. The planet gets its
          watery blue hue from a gas called
          methane found in the planet's atmosphere.
          Neptune and its next-door
          neighbor Uranus are so similar that
          they are sometimes called twins.

Body      Did You Know?

Sun       The sun is a giant spinning ball of hot gas (about 70 percent
          hydrogen, 28 percent helium, and 0.2 percent other elements).
          It has been shining brightly for 4.5 billion years. Enough
          hydrogen remains in the sun's core to keep our star shining-
          providing heat and light-for another 5 billion years. The sun
          is also the largest object in the solar containing more than
          99 percent of the solar system's mass, or amount of matter.
          Its strong gravity, or attracting force, tugs on the planets
          and holds them together. Because of this pull, you would
          weigh thousands of pounds on the surface of the sun.

Mercury   While Mercury orbits quickly around the sun, it spins slowly
          on its axis, or the imaginary line that runs through a
          planet's poles. It takes almost 59 days for Mercury to
          complete one rotation, or movement around its axis. Because
          of this odd combination, there is an interval of 176 days
          between sunrises. As the planet closest to the sun, Mercury
          also has the greatest range in surface temperatures. It
          ranges from over 427[degrees]C (800[degrees]F) when facing
          the sun and dips to as low as -180[degrees]C
          (-300[degrees]F) when facing away.

Venus     Because it is near the sun and blanketed by a dense layer of
          heat-trapping gases, Venus is the hottest planet in the solar
          system. Temperatures soar well over 460[degrees]C
          (870[degrees]F). Also, the air pressure on its surface is 90
          times greater than on Earth's surface. Because of the extreme
          heat, no probe landing on Venus has survived longer than 2
          hours and 7 minutes.

Earth     The third planet from the sun is the largest of the inner or
          terrestrial (solid surface) planets, which include Mercury,
          Venus, Earth, and Mars. It's also the densest (most mass per
          unit volume) planet in the solar system. Earth formed
          approximately 4.5 billion years ago, and is still evolving.
          The first signs of life appeared in Earth's oceans more
          than 3.5 billion years ago.

Moon      The moon is the only extraterrestrial body visited by humans.
          From 1969 to 1972, six Apollo missions sent 12 astronauts to
          the moon's surface. The astronauts collected and returned to
          Earth 840 pounds (382 kilograms) of rock samples.

Mars      Mars is filled with many geological wonders. The planet
          boasts the largest volcano in the solar system: Olympus Mons
          stretches across 373 mi (600 km) and rises about 14 mi
          (22 km) high. It's three times taller than Mount Everest.
          Permanent ice caps at both poles are made of solid carbon
          dioxide, or "dry ice," and water ice. Valles Marineris, a
          system of deep cayons on Mars, extends over a distance equal
          to the length of the entire United States.

Jupiter   Jupiter--along with Uranus, Saturn, and Neptune--is a gas
          giant. Unlike terrestrial planets, a gas giant's surface is
          not solid; it's made of liquid and gases surrounding a small
          solid core. There's an enormous, 300-plus-year-old storm on
          Jupiter called the Giant Red Spot. The storm is so large that
          two Earths would fit inside it. Jupiter has the fastest
          rotation on its axis of any planet in the solar system: One
          rotation takes 9 hours and 55 minutes. It also has at
          least 63 moons.

Saturn    While the other gas giants also have rings, Saturn's rings
          span the farthest. The outermost ring, E ring, stretches out
          to approximately 298,258 mi (480,000 km). But the rings
          aren't thick: estimates range from 30 to 3,300 feet (10
          meters to 1 km). Besides impressive rings, Saturn also has
          at least 56 moons.

Uranus    The third-widest planet's most unusual feature is that its
          axis of rotation is almost horizontal (98 degrees)--Uranus
          spins sideways! As a result, each pole in the planet's
          84-year orbit experiences 42 years of non-stop sunlight
          followed by 42 years of complete darkness. Uranus also
          features at least 12 rings and has 27 known moons.

Neptune   Since its discovery in 1846, Neptune has yet to complete one
          orbit (almost 164 years) around the sun! Triton, the largest
          of Neptune's 13 moons, is surrounded by a thin atmosphere.
          The moon also has geysers on its surface that spew out icy
          material.

Activity A

Match each object in the left column with a fact about the object in
the right column.

1. Sun        a. Its axis of rotation is almost horizontal.
2. Mercury    b. Its soil is rich in iron oxide.
3. Venus      c. It has an oxygen-rich atmosphere.
4. Earth      d. Its orbit around the sun takes 164 years to complete.
5. Moon       e. It has the greatest range in surface temperatures.
6. Mars       f. It was the most distant planet known to humans before
                 the telescope's invention.
7. Jupiter    g. This object is Earth's only natural satellite.
8. Saturn     h. It is the hottest planet in the solar system.
9. Uranus     i. It has a Giant Red Spot that's really a storm.
10. Neptune   j. Its gravity holds all the planets together.

Activity B

Write a science-fiction short story:

You and your crew are on a mission to explore one of the planets of the solar system. Do research to discover five additional fascinating facts about your planned destination. Include them in your story.

Answer Key

Activity A

1. j 2. e 3. h 4. c 5. g 6. b 7. i 8. f 9. a 10. d

Activity B

Answers will vary