Unit 4 Lesson 2 Moon Phases and Eclipses

Unit 4 Lesson 2 Moon Phases and Eclipses Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses Florida Benchmark • SC. 8. E. 5. 9 Explain the impact of objects in space on each other including: 1. The Sun on the Earth including seasons and gravitational attraction, 2. The Moon on the Earth, including phases, tides, and eclipses, and the relative position of each body. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses Round and Round They Go! How are Earth, the moon, and the sun related in space? • Earth spins on its axis and orbits around the sun. • A body that orbits a larger body is called a satellite. • Smaller bodies that travel around planets are natural satellites called moons. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses How are Earth, the moon, and the sun related in space? • Gravity is the force that pulls all bodies that have mass toward other objects. • Earth’s gravitational pull on the moon keeps the moon in orbit, forming the Earth-moon system. • The distance between Earth and the moon is roughly 383, 000 km (238, 000 mi). Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses What does the moon look like from Earth? • The moon is only visible from Earth when it reflects sunlight. • Only one side of the moon, often called the near side, faces Earth. • The moon rotates once on its axis for every 28. 5 days it takes to revolve around Earth. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses What does the moon look like from Earth? • Why do you always see the same side of the moon? Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses It’s Just a Phase! How does the appearance of the moon change? • As the moon revolves around Earth, the portion of the moon that reflects sunlight back to Earth changes. • The lunar phases are changes in the moon’s appearance due to its position in orbit around Earth. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses How does the appearance of the moon change? • Lunar phases cycle monthly and begin with a new moon. • The new moon is hard to see because Earth, the moon, and the sun are lined up, making the moon unlit. • As the moon moves in its orbit, a crescent shape grows larger. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses How does the appearance of the moon change? • The moon waxes, or grows until half of the near side is in sunlight. This is the first quarter. • The gibbous phase is when the near side is more than half-lit but not fully lit. • When the moon is fully lit, it is called a full moon. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses How does the appearance of the moon change? • The lit portion of the moon shrinks, or wanes, during the third week of the cycle. • When the near side is only half-lit in sunlight, it is three-quarters through the cycle. The phase is called the third quarter. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses How does the appearance of the moon change? • When the moon is seen as waning crescent shapes, the cycle is almost complete. • When the moon is again unlit as a new moon, the cycle is complete. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses Exploring Eclipses • An eclipse is an event during which one object in space casts a shadow on another object. • A lunar eclipse occurs when the moon moves through Earth’s shadow. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses Some helpful vocab • The umbra is the darkest part of a shadow. Around the umbra is a spreading cone of lighter shadow called the penumbra. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses How do solar eclipses occur? • When the moon is directly between the sun and Earth, the shadow of the moon falls on a part of Earth and causes a solar eclipse. • When the sun’s light is completely blocked by the moon, it is a total solar eclipse. • Outside the umbra, but within the penumbra, people see a partial solar eclipse. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses How do solar eclipses occur? • The moon’s umbra makes a shadow that is never more than a few hundred kilometers across. • A total eclipse covers only a part of Earth and can only be seen in particular areas. • A total solar eclipse happens somewhere on Earth every one to two years. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 2 Moon Phases and Eclipses How do solar eclipses occur? • Why is a total solar eclipse visible over only a small portion of Earth? Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 3 Earth’s Tides A Rising Tide of Interest What causes tides? • Tides are daily changes in the level of ocean water. • Tides are caused by the difference in the gravitational force of the sun and moon across Earth. • The difference in gravitational force is called the tidal force. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 1 Earth’s Days, Years, and Seasons Spinning in Circles What determines the length of a day? • Each planet spins on its axis. • The spinning of a body, such as a planet, on its axis is called rotation. • The time it takes a planet to complete one full rotation on its axis is called a day. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 1 Earth’s Days, Years, and Seasons What determines the length of a year? • As Earth rotates on its axis, it also revolves around the sun. • The motion of a body that travels around another body in space is called revolution. • Earth completes a full revolution around the sun in 365 ¼ days, or about one year. We have divided the year into 12 months, each lasting 28 to 31 days. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 1 Earth’s Days, Years, and Seasons What conditions are affected by the tilt of Earth’s axis? • The angle at which the sun’s rays strike each part of Earth’s surface changes as Earth moves in its orbit. • When the North Pole is tilted toward the sun, the sun’s rays strike the Northern Hemisphere more directly, and this region is warmer. • When the North Pole is tilted away from the sun, the sun’s rays strike the Northern Hemisphere less directly, and this region is cooler. Copyright © Houghton Mifflin Harcourt Publishing Company

Unit 4 Lesson 1 Earth’s Days, Years, and Seasons change … What causes seasons? • Most locations on Earth experience seasons. Each season is characterized by a pattern of temperature and other weather trends. • We experience seasons due to changes in the intensity of sunlight and the number of daylight hours as Earth revolves around the sun. Copyright © Houghton Mifflin Harcourt Publishing Company