Earth’s perihelion is the place in its orbit where it is closest to the sun. This distance is 147 million km. Earth’s aphelion is the place in its orbit where it is farthest from the sun. This distance is 152 million km. Earth is at its perihelion on about January 3rd each year. It is at its aphelion on about July 4th each year. Earth’s Motions Imagine a line passing through the center of Earth that goes through both poles. This imaginary line is called an axis. Earth spins around its axis in a movement called rotation. Earth also orbits, or revolves around, the sun. This movement is... Show more Earth’s perihelion is the place in its orbit where it is closest to the sun. This distance is 147 million km. Earth’s aphelion is the place in its orbit where it is farthest from the sun. This distance is 152 million km. Earth is at its perihelion on about January 3rd each year. It is at its aphelion on about July 4th each year. Earth’s Motions Imagine a line passing through the center of Earth that goes through both poles. This imaginary line is called an axis. Earth spins around its axis in a movement called rotation. Earth also orbits, or revolves around, the sun. This movement is called revolution. In 1851, long before Earth could be viewed from space, a French scientist named Léon Foucault determined that Earth rotates. He did this by watching the movement of a pendulum. A pendulum is a heavy weight that swings back and forth on a string. Foucault knew that after a pendulum is set in motion, it will keep moving in the same direction. When Foucault observed his pendulum, it seemed to change direction, so he concluded that Earth must be moving beneath the swinging pendulum. Earth requires 23 hours, 56 minutes, and 4 seconds to make one complete rotation on its axis. However, because Earth revolves around the sun at the same time that it is rotating, the planet must turn a little bit more to reach the same position relative to the sun. This explains why the length of a day on Earth is actually 24 hours. At the equator, Earth rotates at its maximum speed of about 1,700 km/h. It rotates more slowly at high latitudes, down to a speed of little more than zero km/h at the poles. For Earth to make one complete revolution around the sun takes 365.24 days. The amount of time Earth—or any planet—takes to revolve around the sun is the definition of a year. The gravitational pull of the sun keeps Earth and the other planets in orbit around it. Like the orbits of the other planets, Earth’s orbit is elliptical rather than circular, so the planet is farther away from the sun at some points in its orbit than others. The closest Earth gets to the sun each year is about 147 million km, which is called perihelion. It occurs on about January 3rd. The farthest Earth gets from the sun each year is about 152 million km, which is called aphelion. It occurs on about July 4th. Earth revolves around the sun at an average speed of about 27 km/s, but it moves more slowly at aphelion and more quickly at perihelion. Show less
Earth’s perihelion is the place in its orbit where it is closest to the sun. This distance is 147 million km. Earth’s aphelion is the place in its orbit where it is farthest from the sun. This distance is 152 million km. Earth is at its perihelion on about January 3rd each year. It is at its aphelion on about July 4th each year.
Earth’s Motions Imagine a line passing through the center of Earth that goes through both poles. This imaginary line is called an axis. Earth spins around its axis in a movement called rotation. Earth also orbits, or revolves around, the sun. This movement is called revolution. In 1851, long before Earth could be viewed from space, a French scientist named Léon Foucault determined that Earth rotates. He did this by watching the movement of a pendulum. A pendulum is a heavy weight that swings back and forth on a string. Foucault knew that after a pendulum is set in motion, it will keep moving in the same direction. When Foucault observed his pendulum, it seemed to change direction, so he concluded that Earth must be moving beneath the swinging pendulum. Earth requires 23 hours, 56 minutes, and 4 seconds to make one complete rotation on its axis. However, because Earth revolves around the sun at the same time that it is rotating, the planet must turn a little bit more to reach the same position relative to the sun. This explains why the length of a day on Earth is actually 24 hours. At the equator, Earth rotates at its maximum speed of about 1,700 km/h. It rotates more slowly at high latitudes, down to a speed of little more than zero km/h at the poles. For Earth to make one complete revolution around the sun takes 365.24 days. The amount of time Earth—or any planet—takes to revolve around the sun is the definition of a year. The gravitational pull of the sun keeps Earth and the other planets in orbit around it. Like the orbits of the other planets, Earth’s orbit is elliptical rather than circular, so the planet is farther away from the sun at some points in its orbit than others. The closest Earth gets to the sun each year is about 147 million km, which is called perihelion. It occurs on about January 3rd. The farthest Earth gets from the sun each year is about 152 million km, which is called aphelion. It occurs on about July 4th. Earth revolves around the sun at an average speed of about 27 km/s, but it moves more slowly at aphelion and more quickly at perihelion.
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