Chapter 5, Lesson 2The Structure of the Solar System

What is the solar system?

• Solar system is a system of objects of, or around the sun (planets and stars)

• Sun is at the center

Galileo Galilei

• 1610 discovered everything revolves around the sun

• A telescopes uses lenses to see distant objects

What is a moon?

• A moon is a object that circles around a planet• Different planets have different numbers and

sizes of moons• Mercury and Venus have no moons, while

Jupiter has at least 63

Ganymede, one ofJupiter’s moons.

Earth’s moon. Mimas, one of Saturn’s moons.

Phobos, one of Mars’moons

Satellites

• A satellite is an object in space that circles around another object

• Moons are also called satellites• Man-made satellites circle around Earth,

providing weather information and are part of communication systems

one of Saturn’s moons

Craters

• When objects in space collide, craters are formed

• Earth’s moon has millions of craters• Impact knocks the surface material of the

moon away• Since the moon has no atmosphere, the objects

that fall toward it do not burn up, as they do in Earth’s atmosphere. This is why the moon has more craters than Earth.

What are the smaller objects in the solar system?

• Asteroids are rocks that revolve around the sun

• Most are located between mars and Jupiter • Most have an irregular shape, like a potato• Some are less than a mile wide, while others

can be up to 500 miles wide

What are the smaller objects in the solar system?

• Comets are a mixture of frozen gases, ice, dust, and rock that move in an irregular circle around the sun.

• Most comets are no more than a few kilometers in diameter. However, as it gets closer to the sun, the sun warms the comet and melts the ice. This results in a coma, or tail being formed.

What are the smaller objects in the solar system?

• Meteoroids are debris that are in the solar system

• Once the Meteoroid enters Earth’s atmosphere, meteors are formed

Review Questions

• How have telescopes improved our knowledge of the solar system?

• What is the difference between a moon and a satellite?• What are asteroids, comets, and meteors?• What does the solar system include?• The sun, planets, and moons are part of the ______.• People in the past believed that the Earth was the center

of the solar system. What is wrong with this idea?• What tool does a scientist use to observe the solar

system?