The Sun: An Important Star 14.7

The Suns Affects on the Earth The Sun is the only star in our solar system. It gives the energy needed by all the Earths plants and animals. Its gravitational pull keeps us in our steady orbit. 1. No life could exist on any planet in our solar system without the energy provided by the Sun. P.452

At night, the temperature drops, the light fades, and other objects become visible. Because the Sun is the closest star to the Earth, you cannot see other stars until the Sun has set.

Where does the Suns Energy come from? The Sun produces energy through a process called 2. Nuclear Fusion - Hydrogen nuclei fuse to form helium nuclei. Inside the Sun the temperature and pressure are so high that substances fuse and form new substances. 3. When the substances fuse together it produces large amounts of heat, light, and other energy that travel from the Sun into space.

Nuclear Fusion Hydrogen nuclei fuse to form helium nuclei. This process produces large amounts of heat, light, and other energy that travel from the Sun into space. 4. The Sun is about 75% hydrogen and 25% helium. paragraphs 3-4 paragraphs 3-4

Nuclear Power (Point Lepreau in St. John) 5. Nuclear power plants do this to create energy for homes, but on a much smaller scale. They use tiny amounts of a metal called uranium to start a nuclear reaction. The reaction releases heat, which is used to make steam. Nuclear power plants dont pollute the air, but their waste is very dangerous. A nuclear accident can poison a large area for thousands of years.

Activity On a blank sheet of paper draw a picture similar to Figure 3 on p.453. On a blank sheet of paper draw a picture similar to Figure 3 on p.453. It should look like a Black Line Master drawing, making sure the lines for the labels are all lined up and neat. It should look like a Black Line Master drawing, making sure the lines for the labels are all lined up and neat. Label all the parts of your drawing. Label all the parts of your drawing. Do questions 1, 2, 7 on p Do questions 1, 2, 7 on p. 453.

Fig. 3 Page 453

P. 453 Questions 1. Describe the difference between a solar flare and a solar prominence. Which affects us and how? A solar flare is an eruption of hot gases from the inner atmosphere of the Suns surface. It travels very quickly and last for only minutes.

A solar prominence is a burst of a huge sheet of gases, also from the inner atmosphere. It is much larger than a flare and may last for days or even weeks. The charged particles from a solar flare affect us in two main ways: They produce the beautiful auroras, and they cause problems in communication systems.

2. Describe the process that occurs in the Suns core to produce so much energy. The process is called nuclear fusion. Inside the Sun it is so hot and the pressure is so high that the substances actually fuse together to form new substances.

7. Why do we consider the Sun to be the most important star? The Sun is the most important star to us because it provides the light energy and heat needed to support life on Earth (us). Tomorrow we will watch a video: TLC – Stars Episode 1