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Chapter 15: Lesson 1- What are some patterns that repeat every day? Close your eyes and imagine… You are floating in space outside the Space Shuttle. The Sun has just risen above the curve of Earth. Look how bright the Sun is in the blackness all around! Sunlight shimmers on the ocean far below. It’s another amazing sunrise. What are these patterns of movement, light, and darkness that you have seen on your space journey? Every day there is light during the day followed by darkness at night. If the day is sunny, you might notice shadows. Day, night, and shadows are caused by light from the Sun and the movement of Earth. The Sun The sun is a star- a giant ball of hot, glowing gases. It is the main source of light and energy for Earth. Earth is very small compared to the Sun. Like the Sun, Earth is shaped like a ball. But unlike the Sun, Earth does not glow or make its own light. The half of Earth’s curved surface facing the Sun is lit by sunlight. The half of Earth’s surface facing away from the Sun is not lit by sunlight and is dark. Day and Night Earth is always moving. One way it moves is that it spins around an imaginary line called an axis. Earth makes one complete spin on its axis, or rotation, every 24 hours. During this time, half of Earth always faces the Sun- this half has day. The half of Earth that is not facing the Sun has night. As Earth rotates a different part of Earth faces the Sun. Shadows A shadow forms on a surface when sunlight hits an object and is blocked. The shadow is an area that is not getting direct light. The shadow has about the same shape as the object that blocks the light. The length and direction of a shadow depend on the time of day. Morning and afternoon shadows are longer than midday shadows. As the Sun moves toward the horizon in the west, shadows stretch toward the east. After the Sun sets, there is no sunlight to make shadows. The sun has just risen in the east. In what direction do the shadows stretch? 1. What star is a source of light and energy on Earth? 2. What is Earth’s axis? 3. What three things are needed to have a shadow? Scientist’s Journal: “The Sun’s Position” Illustrate the position of the Sun in the sky in the early morning, at noon, in the afternoon, and in the late evening. Track the Sun’s position by looking at the shadows it casts. Explain why the Sun is only out in the daytime, and what happens to the Sun at night. Chapter 16: Lesson 1- What are the parts of the solar system? Close your eyes and imagine… Don’t look at it! The Sun has a great amount of energy. You should never look directly at it. The Sun is the fiery center of our solar system. This huge ball of energy holds our solar system together. But what’s going on underneath its surface? The solar system includes the Sun, the planets, and other objects that travel around it. The Sun gives off energy that moves out in all directions through space. The Sun The Sun is a ball of hot, glowing gases called plasma. It is a star. The Sun looks larger and brighter than stars you see at night because it is a lot closer to Earth. How big is the Sun? Large enough to fit one million Earths inside of it! Wider than the length of 15,000,000 football fields! The temperature on the surface of the Sun is 5,500 degrees Celsius. The center is millions of degrees hot. It is so hot that gas particles that have a positive charge collide and join. This releases a lot of energy. Energy that travels from the Sun through space includes sunlight. 1. Why is the Sun so bright and hot? 2. Why don’t the stars at night look as bright as the Sun? Scientist’s Journal Draw a picture of the solar system, showing the Sun at the center. Use pages 456-457 as a reference. Label each planet. Chapter 12: Lesson 4- What are star patterns? Think about being outside on a clear, dark night. You see thousands of twinkling stars. Some stars are brighter than others. Some are easier to see. But they all look so small in the sky because they are trillions of miles away. Some of these stars are actually larger than the Sun! The stars that are farthest away are the dimmest and the hardest to see. You cannot see many starts at all without certain tools to help you. Binoculars and telescopes make studying patterns of stars easier. They magnify objects that are far away. They make objects look larger and easier to see. If you use a telescope, you can see many more stars than with your eyes alone. Binoculars and Telescopes Scientists use different kinds of telescopes. These telescopes are tubes, mirrors that make light reflect, and lenses that bend light or refract it. All these parts help bring as much light as possible into the telescope. The result is a larger and clearer view of objects in the sky. Other kinds of telescopes do not collect light. They collect other kinds of waves, such as radio waves. A look inside the Keck telescope in Hawaii. The twin Keck telescopes at the W. M. Keck Observatory in Mauna Kea, Hawaii. 1. What are two tools that can help you see stars? 2. Why do we use telescopes to look at the stars? Scientist’s Journal The night sky is filled with stars that vary in brightness, size, and distance from Earth. Sometimes they make pictures and patterns. Draw a picture of some star patterns that you have seen. Describe, using words, what you think they look like. Chapter 12: Lesson 2- How does force affect motion? Forces act on objects to change their motions. A force can involve two or more objects that contact each other. Other forces can act on an object without touching it. If the bat makes contact with enough force, the ball’s change in speed and direction could take it out of the ballpark. This shopping cart needs little force to start it moving, but wait until it’s full. The Causes of Motion A force is any push or pull. A force can change an object’s position or the direction of its motion. Most of the forces we use are contact forces. When you push or pull an object, you must come in contact with, or touch, the object. How much an object changes its position and speed depends on how much force is used. The greater the force on an object, the greater the change in motion. She is using more force because she is angry. Because the force is greater, the change in motion is greater. These people are playing tug-of-war. Both sides are exerting force by pulling. The rope is changing motion every time the force is greater on one side. Effects of Mass How an object moves also depends on how much mass it has. Remember the empty grocery cart? You don’t need much force to begin pushing it. But as you fill it up with groceries, the cart gains more mass. Then you have to use more force to make it move. Effects of Friction While your grocery cart moves down the aisle, its wheels rub against the floor. This causes friction. Friction is a contact force that goes against the motion of an object. It can cause moving objects to slow down or stop. The amount of friction between two objects depends on their surfaces. Pushing a grocery cart over smooth tiles in the story is pretty easy. But you will need more force pushing the cart across the asphalt parking lot. Sometimes friction is a helpful force. If you’ve been skating or sledding, you may have used friction to help you slow down. 1. What is a force? 2. What is friction? Scientist’s Journal Choose a sport or another activity that you enjoy doing. Brainstorm what happens during this game and identify any forces that they use in the sport. Write down your descriptions and illustrate your actions. Use diagrams and labels to make you illustrations clear.