Universe Cycle - Solar System (K)
Pre Lab 

  • Distinguishing the different planets.
  • Exploring our Solar System.
  • Earth
  • Moon
  • planets
  • Solar System
  • Sun
  • How many Planets? by Blueford and Doherty
  • worksheet
  • crayons
  • Solar System Placemats
  • clay or play dough
  • toothpicks

Students make planets with paper and clay.


The Universe is everything in outer space, including stars, black holes, quasars, and galaxies. The Solar System is part of the Universe. It is composed of the Sun, the nine planets, and many small objects like comets and asteroids. The Sun radiates light while planets and asteroids are visible only by reflected sunlight.

The planets are all rotating around their own axis, as they revolve around the Sun. The planets are divided into inner and outer planets. The inner planets are all composed of "rock," just like the Earth. The outer planets, except for Pluto, are composed of gas.  We are learning new information every year.

Mercury is the closest planet to the Sun. It orbits the Sun quickly, once every 88 days. It rotates slowly, however, only once every 59 days. Mercury is small, about 4850 kilometers (~3000 miles) in diameter. Because Mercury is so close to the Sun, the side of its surface that faces the Sun is very hot, ~700oK. The surface of Mercury is gray to orange in color, and is covered with craters. Mercury is named for a mythical god who ran very fast.

Venus, the second planet away from the Sun, is Earth’s closest neighbor. It is about the same size as the Earth, a little over 12,000 kilometers (7300 miles) in diameter. Venus has a very thick atmosphere, composed largely of sulphuric acid and CO2. We could not breathe on Venus, because the atmosphere would be very toxic to humans. This atmosphere gives Venus a brownish-yellow color. It also traps heat (the greenhouse effect) making the surface of Venus the hottest in the Solar System, about 750oK. Venus rotates very slowly, taking 243 days to complete one turn. It is named for the Roman goddess of love.

Earth is a little more than 12,000 kilometers in diameter. It differs from the other planets because it has liquid water on its surface, maintains life, and has active plate movement. It rotates on its axis every 24 hours (a day) and revolves around the Sun every 365 days (a year). The Earth has one moon.

Mars is a little more than half the size of the Earth, having a diameter of 6,790 kilometers. It takes Mars 687 days to revolve once around the Sun. It rotates at about the same speed as the Earth, taking 24.6 hours. Mars has a very thin atmosphere which is composed largely of CO2. Its surface is very cold, and is covered with craters, volcanoes, and large canyons. Mars is reddish in color. Mars has two small moons. It is named for the Roman god of war.

Jupiter is the largest planet in the Solar System, with a diameter of 142,980 kilometers, more than 11 times wider than the Earth. Jupiter orbits the Sun once every 12 years. It rotates very fast, in only 10 hours. Its surface is made up of gas (mostly hydrogen), so that if you landed on the surface you would sink into it. Jupiter probably has a core of metallic hydrogen and rock, although evidence for this is theoretical. The outer gaseous part of Jupiter is broken into bands of white, yellow, red, and brown clouds. Huge oval-shaped storms also occur on the surface. Jupiter has at least 16 moons. Jupiter is named for the Roman supreme god of heaven.

Saturn is well known for its system of three rings. It is a large planet: at 120,536 kilometers it is only a little smaller than Jupiter. It revolves around the Sun in 12 years, and rotates a little more than 10 hours. Like Jupiter, Saturn is composed mostly of gas, and has a core composed of rock and metallic hydrogen. The surface of Saturn looks banded, and has a brown-yellow, butterscotch color. Saturn’s rings are probably composed of small particles of ice and rock. Saturn has at least 20 moons. It is named for the Roman god of agriculture.

Uranus is 51,118 kilometers in diameter, about 4.4 times the size of the Earth. It revolves around the Sun slowly, taking 84 years to complete one orbit. It rotates in about 17 hours. It is covered by a thick layer of gas, and has a fairly uniform blue-green color. Uranus has both at least 15 satellites, and is surrounded by a system of nine rings. It is named for another Roman god, the grandfather of Jupiter

Neptune is slightly smaller than Uranus, with a diameter of 49,500 kilometers. It circles the Sun once every 165 years, and rotates in 16 hours. Its atmosphere appears blue , and is marked by large dark blue storm systems. It is surrounded by a system of five rings and at least 8 moons. Neptune is named for the Roman god of the ocean.

Pluto is the most distant "official" planet from the Sun. It has an eccentric, oval-shaped orbit, which is tilted with respect to the rest of the Solar System. Pluto revolves around the Sun in 248 years, and rotates in a period of 6.4 days. Pluto is probably composed of rock. Its surface and color are unknown. It has one large moon called Charon.. Pluto is named for the Roman god of outer darkness.

In 2004, "Sedna" was discovered which is now the most distinct body that orbits the Sun.  It is 3 times as far as Pluto.  Sedna is slightly smaller than Pluto.  It is not officially a planet at this time. 

  1. Discuss the nine planets of the Solar System by reading How many Planets? with the students.  Go over a few of the "facts," gearing the discussion toward the worksheet or pictures of the planets. Use the Solar System placemats to help students locate the different planets and to understand their orbits.

    Mercury: is the closest to the Sun, it is not very big

    Venus: has a very spooky atmosphere, that makes this planet the hottest in the Solar System

    Earth: is one of the planets, noted for its forest, water, and life

    Mars: is about the same size as Earth

    Jupiter: is the largest planet, and it not made up of just rocks, it is made in part of gas

    Saturn: is noted for its rings, and it like Jupiter is more of a gas planet

    Uranus: has some rings, and is a gas planet also

    Neptune: has some rings, and it a gas planet

    Pluto: terrestrial planet,  has only one moon, farthest planet away from Sun

  2. Students can color the planets on the worksheet. Note that the planets are not to scale. Have the students cut out their pictures, and place them on top of the correct planet on the Solar System Placemat.
  3. Students can use clay or play dough to make models of the planets. Have the students try to make models that reflect the real sizes of the planets, as shown on the the Solar System Placemat. You may have them mount their models on toothpicks embedded in clay at its base.


    250 ml flour
         125 ml salt
         5 ml cream of tartar
         250 ml water
         about 1/2 ml food coloring
         about 1/2 ml oil

    Cook this mixture, over medium heat, stirring it constantly until it forms a dough-like texture. Knead it briefly, after the mixture has cooled. Multiply this recipe by 6 to get enough for a class of 30 students, but it should be made in two batches. Large amounts of dough are difficult to stir because the mixture becomes firm. Store the play dough in a plastic bag or a margarine container.

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