Download Planets and other Objects in Space

Planets and other Objects in Space
Science ‐ Lower 5th Grade
St. George's College
October, 2008
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Brainstorming: What is the Moon?
orbits
forms
attracts
causes
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Objectives
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Describe and explain the motions of Earth and the Moon.
Relate a day and year to the motions of Earth.
Describe the causes of the seasons.
Explain the motions of the planets.
Distinguish among planets, asteroids, and comets.
Explain how the planets are divided into two groups, inner planets and outer planets.
Note: Most of the objectives will be covered in class, however the student must be responsible for those objectives
not covered or concluded.
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Vocabulary
Satellite: an object that moves around another object in space; the moon is a satellite of Earth.
Orbit: the path that an object such as a planet makes as it revolves around a second object.
Phase: one of the different shapes the moon seems to have as it orbits around Earth.
Revolution: the movement of any object in an orbit, such as Earth moving around the Sun.
Axis: an imaginary line which runs through both poles of a planet.
Rotation: the motion of a planet or other object as it turns on its axis.
Solar system: a group of objects in space that move around a central star.
Star: a huge, burning sphere of gases; for example, the Sun.
Planet: a large object that moves around a star.
Asteroid: a small rocky object that moves around the Sun.
Comet: a small mass of dust and ice that orbits the Sun in a long, oval‐shaped path.
Inner planets: the planets closest to the Sun; Mercury, Venus, Earth, and Mars.
Outer planets: the planets farthest from the Sun; Jupiter, Saturn, Uranus, Neptune, and Pluto.
Gas giants: planets which are large spheres made up mostly of gases; for example, Jupiter, Saturn, Uranus, and Neptune.
Note: Most of the vocabulary words will be covered in class, however the student must be responsible for those words
not covered or concluded.
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Lesson 1:
How do Earth and its
Moon move?
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Motions of the Moon
• The moon is a natural satellite of Earth. A satellite is an object that moves around another object in space.
• The moon moves around Earth in a certain path or orbit. It takes a little more than 28 days for the moon to complete its orbit.
• The moon doesn't give off its own light, it reflects light from the sun.
• As the moon moves through its orbit, different amounts of its lit half can be seen from Earth. That's why the moon seems to have different shapes, or phases.
• The moon's cycle of phases takes just over 28 days to complete.
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Motions of Earth
• Just as the moon moves around Earth, Earth moves around the Sun. Just as the moon is a satellite of the Earth, Earth is a satellite of the Sun.
• The movement of Earth around the Sun is called its revolution. It takes Earth one year to complete a revolution.
• As Earth revolves around the Sun, it is also spinning around an imaginary line or axis, runs through the center of earth from the North Pole to the South Pole.
• It takes 24 hours, or one day, for earth to complete one rotation on its axis. This rotation causes day and night.
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Earth and the Seasons
• Earth's axis is slightly tilted. This tilt, along with the constant movement of earth around the Sun, causes seasons.
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Lesson 2:
How do Objects move in
the Solar System?
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The Sun
• A solar system is a group of objects in space that move around a central star. Our sun is a star, a burning sphere of gases.
• The Sun (more than 1 million kilometers in diameter) is the largest object in the solar system.
• The sun puts out a lot of energy in all directions. In fact, it is the source of almost all the energy in our solar system.
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Other objects in our Solar System
• A planet, such as earth and its seven neighbors, is a large object that moves around a star.
• Most planets in our solar system also have at least one natural satellite, or moon.
• Asteroids and comets are other objects that move around the sun. Asteroids are small and rocky. Most of them are scattered in a large area between the orbit paths of Mars and Jupiter.
• A comet is a small mass of dust and ice that orbits the sun in a long, oval‐shaped path.
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Paths around the Sun
• An object revolves as it moves around another object.
• The time for one complete orbit by a planet around the sun is its year.
• The orbits of the planets are not circles, they are a little bit elliptical, or oval, in shape.
The astronomical unit (AU) is a unit of length based on the distance from the Earth to the Sun (nearly 150 million kilometers).
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Lesson 3:
What are the Planets like?
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Planets ‐ Animation
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The Inner Planets
• The area of the asteroid belt can be thought of as a dividing line between two groups of planets, the inner and outer planets.
• The inner planets (Mercury, Venus, Earth, and Mars) lie between the sun and the asteroid belt.
• Like the asteroids, the inner planets are rocky and dense. Unlike the asteroids, these planets are large and, except for Mercury, have atmospheres.
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The Inner Planets
• Mercury, the closest planet to the Sun, is about the size of Earth's moon. Mercury is covered with craters, even looks like the moon. It has very small amounts of gas that are not enough to make up an atmosphere.
• Venus, second planet from the Sun, is about the same size as Earth, but very different features. Venus is dry and has a thick atmosphere that traps heat (surface T°=475°C). The thick atmosphere presses down on Venus with a weight (force) 100 times that of Earth's atmosphere. Venus rotates on its axis in a direction opposite from that of Earth's rotation.
• Earth, third planet from the Sun, is the largest inner planet. it has a natural satellite, and is the only planet with liquid water, and the only known planet that supports life. Its atmosphere absorbs part of the solar energy to keep the planet at a temperature suitable to support life.
• Mars, fourth planet from the Sun, is called the Red Planet because its soil is dark red‐brown. Mars has two moons and the largest volcano in the solar system, Olympus Mons. Although liquid water has not been found, it is believed that liquid water once existed there.
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Olympus Mons ‐ Mars
Maxwell Montes ‐ Venus
Mount Everest ‐ Earth
Height: 27 km (27000 m)
Base: over 550 km diameter
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The Outer Planets
• The outer planets (Jupiter, Saturn, Uranus, and Neptune). These planets are large spheres made up mostly of gases. Because of this, these planets are often called the gas giants.
• Jupiter is the largest planet in our solar system. A thin ring that is hard to see surrounds it. At least 16 moons orbit around it. Its atmosphere is very active. Its energy causes a circular storm known as the Great Red Spot, is like a hurricane that has lasted more than 300 years, it is so big that 3 Earths could fit there.
• Saturn is known for its wide and bright rings. Saturn has at least 18 moons.
• Uranus is a blue‐green ball of gas and liquid, with at least 21 moons as well as faint rings around it.
• Neptune has at least 8 moons and a faint ring. it also has circular storms.
• Pluto is a dwarf‐planet, not a gas planet. It has a rocky surface that is probable covered by frozen gases.
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Moons and Rings
• Every planet except Mercury and Venus has at least one natural satellite, or moon.
• Besides having moons, each of the gas giants has a system of rings. 22