Presentation on theme: "Chapter: Earths Place in Space Table of Contents Section 3: Earth and the Solar SystemEarth and the Solar System Section 1: Earths Motion and Seasons."— Presentation transcript:
Chapter: Earths Place in Space Table of Contents Section 3: Earth and the Solar SystemEarth and the Solar System Section 1: Earths Motion and Seasons Section 2: Earths MoonEarths Moon
In the past, some people thought that the Sun, the Moon, and other objects in space moved around Earth each day. Now it is known that some of the motions of these objects, as observed from Earth, are really caused by Earths movements. Earths Physical Data 1 1 Earths Motion and Seasons
Pictures from space show that Earth is shaped like a ball, or a sphere. Spherical Earth 1 1 A sphere (SFIHR) is a three- dimensional object whose surface at all points is the same distance from its center. Earths Motion and Seasons
More proof of Earths shape is that Earth casts a curved shadow on the Moon during a lunar eclipse. Something flat, like a book, casts a straight shadow, whereas objects with curved surfaces cast curved shadows. Evidence for Earths Shape 1 1 Earths Motion and Seasons
Gravity is a force that attracts all objects toward each other. Large objects in space, such as planets and moons often are spherical because of how they formed. Influence of Gravity 1 1 At first, particles collide and stick together randomly. However, as the mass increases, gravity plays a role. Particles are attracted to the center of the growing mass, making it spherical. Earths Motion and Seasons
Earths shape is not a perfect sphere. It bulges slightly at the equator and is somewhat flattened around the poles. Almost a Sphere 1 1 Earths Motion and Seasons
Almost a Sphere 1 1 This causes Earths circumference at the equator to be a bit larger than Earths circumference as measured through the north and south poles. The circumference of Earth and some other physical properties are listed in this table. Earths Motion and Seasons
Almost a Sphere Earths Motion and Seasons 1 1
Earths geographic poles are located at the north and south ends of Earths axis. Motions of Earth Earths Motion and Seasons 1 1
Motions of Earth Earths Motion and Seasons 1 1 Earths axis is the imaginary line drawn from the north geographic pole through Earth to the south geographic pole.
The spinning of Earth on its axis, called rotation, causes you to experience day and night. Motions of Earth Earths Motion and Seasons 1 1
Earths Orbit Earths Motion and Seasons 1 1 As it rotates on its axis each day, Earth also moves along a path around the Sun. This motion of Earth around the Sun is called revolution.
Earths Orbit Earths Motion and Seasons 1 1 What happens on Earth that is caused by its revolution?
Earth is really a satellite of the Sun, moving around it along a curved path called an orbit. Seasons Earths Motion and Seasons 1 1 As Earth moves along in its orbit, the way in which the Suns light strikes Earths surface changes.
Earths elliptical orbit causes it to be closer to the Sun in January and farther from the Sun in July. Seasons Earths Motion and Seasons 1 1 The amount of energy that specific places on Earth receive varies quite a lot.
Earths axis forms a 23.5-degree angle with a line perpendicular to the plane of its orbit around the Sun. Earths Tilt Earths Motion and Seasons 1 1 Because of this, there are more daylight hours for the hemisphere tilted toward the Sun.
Sunlight strikes the hemisphere tilted toward the Sun at a higher angle, that is, closer to 90 degrees. Earths Tilt Earths Motion and Seasons 1 1
Earths Tilt Earths Motion and Seasons 1 1 Sunlight strikes the hemisphere tilted away from the Sun at a lower angle. This lessens solar radiation and brings winter.
Twice during the year, the Sun reaches its greatest distance north or south of the equator and is directly over either the Tropic of Cancer or the Tropic of Capricorn. Solstices Earths Motion and Seasons 1 1 These times are known as the summer and winter solstices.
Summer solstice is when the Sun is highest in the sky at noon. Solstices Earths Motion and Seasons 1 1 The opposite of this for each hemisphere is winter solstice, which is when the Sun is lowest at noon.
At an equinox, (EE kwuh nahks) when the Sun is directly above Earths equator, the lengths of day and night are nearly equal all over the world. Equinoxes Earths Motion and Seasons 1 1 During equinox, Earths tilt is neither toward nor away from the Sun.
Section Check 1 1 Question 1 What evidence suggests that Earth is round? Answer Objects with curved surfaces cast curved shadows and Earth casts a curved shadow on the Moon during a lunar eclipse. Pictures from space show Earth as a ball or a sphere. FL: SC.E.1.3.2
1 1 Section Check Question 2 Which is responsible for the change in seasons? A. Earths orbit B. Earths revolution C. Earths rotation D. summer solstice FL: SC.E.1.3.1
1 1 Section Check Answer The answer is B. A revolution is completed when Earth completes one complete trip around the Sun. It takes one year for Earth to travel around the Sun. FL: SC.E.1.3.1
1 1 Section Check Question 3 What is it called when the length of day and night are equal all over the world? A. equinox B. lunar eclipse C. revolution D. solstice FL: SC.E.1.3.1
1 1 Section Check Answer The answer is A. An equinox occurs when the Sun is directly above Earths equator. During an equinox, Earths tilt is neither toward nor away from the Sun and the length of day and night all over the world is nearly equal. FL: SC.E.1.3.1