Presentation on theme: "Chapter: Earth’s Place in Space"— Presentation transcript:
1Chapter: Earth’s Place in Space Table of ContentsChapter: Earth’s Place in SpaceSection 1: Earth’s Motion and SeasonsSection 2: Earth’s MoonSection 3: Earth and the Solar System
2Earth’s Motion and Seasons 1Earth’s Physical DataIn 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 Earth’s movements.
3Earth’s Motion and Seasons 1Spherical EarthPictures from space show that Earth is shaped like a ball, or a sphere.A sphere (SFIHR) is a three-dimensional objectwhose surface at all points is the same distance from its center.
4Evidence for Earth’s Shape Earth’s Motion and Seasons1Evidence for Earth’s ShapeMore proof of Earth’s 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.
5Earth’s Motion and Seasons 1Influence of GravityGravity 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.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.
6Earth’s Motion and Seasons 1Almost a SphereEarth’s shape is not a perfect sphere. It bulges slightly at the equator and is somewhat flattened around the poles.
7Earth’s Motion and Seasons 1Almost a SphereThis causes Earth’s circumference at the equator to be a bit larger than Earth’s circumference as measured through the north and south poles.The circumference ofEarth and some otherphysical properties are listed in this table.
9Earth’s Motion and Seasons 1Motions of EarthEarth’s geographic poles are located at the north and south ends of Earth’s axis.
10Earth’s Motion and Seasons 1Motions of EarthEarth’s axis is the imaginary line drawn from the north geographic pole through Earth to the south geographic pole.
11Earth’s Motion and Seasons 1Motions of EarthThe spinning of Earth on its axis, called rotation, causes you to experience day and night.
12Earth’s Motion and Seasons 1Earth’s OrbitAs it rotates on its axis each day, Earth also moves along a path around the Sun. This motion of Earth around the Sun is calledrevolution.
13Earth’s Motion and Seasons 1Earth’s OrbitWhat happens on Earth that is caused by its revolution?
14Earth’s Motion and Seasons 1SeasonsEarth is really a satellite of the Sun, moving around it along a curved path called an orbit.As Earth moves along in its orbit, the way in which the Sun’s light strikes Earth’s surface changes.
15Earth’s Motion and Seasons 1SeasonsEarth’s elliptical orbit causes it to be closer to the Sun in January and farther from the Sun in July.The amount of energy that specific places on Earth receive varies quite a lot.
16Earth’s Motion and Seasons 1Earth’s TiltEarth’s axis forms a 23.5-degree angle with a line perpendicular to the plane of its orbit around the Sun.Because of this, there are more daylight hours for the hemisphere tilted toward the Sun.
17Earth’s Motion and Seasons 1Earth’s TiltSunlight strikes the hemisphere tilted toward the Sun at a higher angle, that is, closer to degrees.
18Earth’s Motion and Seasons 1Earth’s TiltSunlight strikes the hemisphere tilted away from the Sun at a lower angle. This lessens solar radiation and brings winter.
19Earth’s Motion and Seasons 1SolsticesTwice 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.These times are known as the summer and winter solstices.
20Earth’s Motion and Seasons 1SolsticesSummer solstice is when the Sun is highest in the sky at noon.The opposite of this for each hemisphere is winter solstice,which is when the Sun is lowest at noon.
21Earth’s Motion and Seasons 1EquinoxesAt an equinox, (EE kwuh nahks) when the Sun is directly above Earth’s equator, the lengths of day and night are nearly equal all over the world.During equinox, Earth’s tilt is neither toward nor away from the Sun.
22Question 1 Answer 1 What evidence suggests that Earth is round? Section Check1Question 1What evidence suggests that Earth is round?AnswerObjects 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
23Question 2 1 Which is responsible for the change in seasons? Section Check1Question 2Which is responsible for the change in seasons?A. Earth’s orbitB. Earth’s revolutionC. Earth’s rotationD. summer solsticeFL: SC.E.1.3.1
24Section Check1AnswerThe 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
25Section Check1Question 3What is it called when the length of day and night are equal all over the world?A. equinoxB. lunar eclipseC. revolutionD. solsticeFL: SC.E.1.3.1
26Section Check1AnswerThe answer is A. An equinox occurs when the Sun is directly above Earth’s equator. During an equinox, Earth’s 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