Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Copyright © Houghton Mifflin Harcourt Publishing Company 1

Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Florida Benchmarks SC.4.E.5.1 Observe that the patterns of stars in the sky stay the same although they appear to shift across the sky nightly, and different stars can be seen in different seasons. SC.4.E.5.3 Recognize that Earth revolves around the Sun in a year and rotates on its axis in a 24-hour day. SC.4.E.5.4 Relate that the rotation of Earth (day and night) and apparent movements of the Sun, Moon, and stars are connected. Copyright © Houghton Mifflin Harcourt Publishing Company 2

Day and Night The Earth rotates, or spins. Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Day and Night The Earth rotates, or spins. This spinning causes day and night. Earth rotates from west to east once about every 24 hours. Copyright © Houghton Mifflin Harcourt Publishing Company 3

Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Day and Night An imaginary pole that runs through Earth’s center is called Earth’s axis. It runs through the center of Earth from the North Pole to the South Pole. Earth rotates on its axis. Copyright © Houghton Mifflin Harcourt Publishing Company 4

Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Day and Night As Earth rotates, one side of Earth faces the sun. This side of Earth has daytime. The other side of Earth faces away from the sun. That side of Earth has nighttime. Copyright © Houghton Mifflin Harcourt Publishing Company 5

Seasons Earth revolves around the sun in a path called an orbit. Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Seasons Earth revolves around the sun in a path called an orbit. Earth takes about 365 days to make one orbit around the sun. Earth’s axis is tilted to one side. The tilt of Earth’s axis and its orbit cause the seasons. Copyright © Houghton Mifflin Harcourt Publishing Company 6

Seasons Earth is divided into halves called hemispheres. Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Seasons Earth is divided into halves called hemispheres. The upper half is the Northern Hemisphere. The lower half is the Southern Hemisphere. The seasons are opposite in the Northern and Southern hemispheres. Copyright © Houghton Mifflin Harcourt Publishing Company 7

Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Seasons When one hemisphere is tilted toward the sun, that hemisphere has spring or summer. When a hemisphere tilts away from the sun, that hemisphere has fall or winter. As Earth orbits the sun, the two hemispheres are tilted toward and away from the sun. Copyright © Houghton Mifflin Harcourt Publishing Company 8

Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Patterns in the Sky A constellation is a group of stars that seems to form a pattern in the night sky. Copyright © Houghton Mifflin Harcourt Publishing Company 9

Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Patterns in the Sky The early Greeks named constellations after animals or people from myths. The Big Dipper is part of a constellation called Ursa Major, or Great Bear. Orion is a constellation named after a hunter in a Greek myth. Copyright © Houghton Mifflin Harcourt Publishing Company 10

Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Patterns in the Sky Constellations seem to move across the night sky as Earth rotates on its axis. Stars above the North Pole seem to move in a circle. Copyright © Houghton Mifflin Harcourt Publishing Company 11

Unit 2 Lesson 1 How Does Earth Rotate and Revolve in Space? Patterns in the Sky The positions of the constellations seem to change with the seasons. This is because we see different parts of space as Earth revolves around the sun. Copyright © Houghton Mifflin Harcourt Publishing Company 12