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Encyclopedic Entry Vocabulary

Rotation describes the circular motion of an object around its center. There are different ways things can rotate.

Rotation of the Earthre

A very familiar kind of rotation is when a spherical, three-dimensional object turns around an invisible line inside its center. This center is called an axis. Spinning basketballs turn around an axis. Globes turn around an axis. The Earth itself spins on an axis.

The Earth's axis is vertical, meaning it runs up and down. (A rolling log, on the other hand, has a horizontal axis, meaning it runs sideways.) The Earth's axis runs from the North Pole to the South Pole. It takes the Earth 24 hours, or one day, to make one complete rotation around this invisible line.

As the Earth rotates, each area of its surface gets a turn to face and be warmed by the sun. This is important to all life on Earth. The sun affects everything from the weather we experience to the food we eat, and even our health. If the Earth did not rotate, one half of the Earth would always be hot and bright, and the other part would be frozen and dark.

The Earth also moves around the sun. This movement is called a revolution, which is different from rotation. Objects rotate around an axis, but revolve around other objects. So the Earth rotates around its axis as it revolves around the sun. It takes the Earth 365 days, or one year, to complete a revolution.

Leftover momentum from when planets were forming makes the Earth, and all planets in the solar system, rotate and revolve. As the solar system formed, many moving particles clustered together. They formed a spinning mass. This mass eventually split into different bodies- planets, moons, asteroids, and comets. All these bodies revolve around the sun. In addition, all planets kept their own rotating motion, including the Earth.

The Earth rotates around its axis at a rate of about 1,600 kilometers (1,000 miles) an hour. It revolves around the sun at a rate of 107,800 kilometers (67,000 miles) an hour.

Other Kinds of Rotation

Planets are not the only round objects that rotate. Amusement park rides, such as Ferris wheels or carousels, also rotate. The Ferris wheel rotates around a horizontal axis, and the carousel rotates around a vertical one. Wheels on a car rotate around a strong horizontal bar called an axle. The axle runs from one side of the vehicle to the other, connecting the front wheels to each other and the back wheels to each other.

Many household items rotate, including sprinkler heads, beaters on a mixer, blades on a ceiling fan, and doorknobs.

There are some things that rotate without a specific axis. Farmers use crop rotation to help the soil stay healthy and plants receive the right nutrients from season to season. Crop rotation means growing things in a different spot each year. This helps prevent disease and encourages the soil to be fertilized by different crops. For example, cabbage, broccoli, and sprouts are in the same plant family. If they were grown in the same place year after year, they could all develop clubroot disease, weakening or killing the crop and damaging the soil. The field itself acts as an axis, with different crop s being rotated in at different times.

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The audio, illustrations, photos, and videos are credited beneath the media asset, except for promotional images, which generally link to another page that contains the media credit. The Rights Holder for media is the person or group credited.

Writers

Kim Rutledge
Tara Ramroop
Diane Boudreau
Melissa McDaniel
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrators

Mary Crooks, National Geographic Society
Tim Gunther

Editors

Jeannie Evers, Emdash Editing
Kara West

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

Last Updated

June 2, 2011

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Writers

Kim Rutledge
Tara Ramroop
Diane Boudreau
Melissa McDaniel
Santani Teng
Erin Sprout
Hilary Costa
Hilary Hall
Jeff Hunt

Illustrators

Mary Crooks, National Geographic Society
Tim Gunther

Editors

Jeannie Evers, Emdash Editing
Kara West

Educator Reviewer

Nancy Wynne

Producer

Caryl-Sue, National Geographic Society

Sources

Dunn, Margery G. (Editor). (1989, 1993). "Exploring Your World: The Adventure of Geography." Washington, D.C.: National Geographic Society.

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This lists the logos of programs or partners of NG Education which have provided or contributed the content on this page. Powered by Encyclopedic Entry Vocabulary Rotation describes the circular motion of an object around its center. There are different ways things can rotate.

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Although often confused, there is a distinct and important difference in the concepts of revolution and rotation. Earth rotates on its axis as it revolves around the .

Earth rotates about its axis at approximately 15 angular degrees per hour. Rotation dictates the length of the diurnal cycle (i.e, the day/night cycle), creates "time zones" with differing local noons, and also causes the apparent movement of the Moon , stars, and planets across the " celestial sphere". The rotation of Earth is eastward (from west to east) making the apparent rotation of the celestial sphere from east to west.

The rates of rotation and revolution are functions of a planet's mass and orbital position. For example, the mass of Jupiter is approximately 317.5 times Earth's mass and the rotation time (the time for Jupiter to revolve once about its axis) is approximately nine hours.

Earth takes approximately 365.25 days to complete one revolution around the Sun in a slightly elliptical orbit with the Sun at one focal point of the ellipse. Ranging between the extremes of perihelion (closest approach) in January and aphelion (most distant orbital position) in July, Earth's orbital distance from the Sun ranges from approximately 91.5 to approximately 94 million miles (147151 million km), respectively. Although these distances seem counterintuitive to residents of the Northern Hemisphere who experience summer in July and winter in Januarythe seasons are not nearly as greatly affected by distance as they are by changes in solar illumination caused by the fact that Earth's polar axis is inclined 23.5 degrees from the perpendicular to the ecliptic (the plane of the solar system through or near which most of the planet's orbits travel) and because the Earth exhibits parallelism (currently toward Polaris, the North Star) as it revolves about the Sun.

At the extreme of the solar system, Pluto, usually the most distant planet (i.e., at certain times Neptune's orbit actually extends farther than Pluto's orbit) takes approximately 247 Earth years (the time it takes the Earth to revolve about the Sun) to complete one orbital revolution about the Sun.

Rotation, revolution, polar tilt, parallelism, and Earth's oblate spheroid shape combine to produce an unequal distribution of solar energy , the changing of seasons, the changing lengths of day and night, and influence the circulation of the atmosphere and oceans .

In addition to Earth's rotation about the Sun, the solar system is both moving with the Milky Way galaxy and revolving around the galactic core.

See also Celestial sphere: The apparent movements of the Sun, Moon, planets, and stars

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revolution and rotation
although often confused

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there is a distinct and important difference in the concepts of revolution and rotation. earth rotates on its axis as it revolves around the sun .

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Revolution and rotation Although often confused, there is a distinct and important difference in the concepts of revolution and rotation. Earth rotates on its axis as it revolves around the Sun . Source for information on Revolution and Rotation: World of Earth Science dictionary.

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Rotation and Revolution of Earth - Movements of the Earth - Earth's Revolution & Rotation

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Earth's Rotation & Revolution: Crash Course Kids 8.1

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the movement or path of the earth or a heavenly body turning on its axis. one complete turn of such a body.

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Rotation is the process or act of turning or circling around something. An example of rotation is the earth's orbit around the sun. 

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Rotation is the process or act of turning or circling around something. An example of rotation is the earth's orbit around the sun.

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Rotation" refers to an object's spinning motion about its own axis. "Revolution" refers the object's orbital motion around another object. For example, Earth rotates on its own axis, producing the 24-hour day.

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Rotation of the Earth is its turning on its axis. Revolution is the movement of the Earth around the Sun. ... The Earth's axis of rotation is tilted by 23.5 degrees. This tilt causes the different seasons of the year.