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Earth's rotation axis moves with respect to the fixed stars (inertial space); the components of this motion are precession and nutation. It also moves with respect to Earth's crust; this is called polar motion. Precession is a rotation of Earth's rotation axis, caused primarily by external torques from the gravity of the Sun, Moon and other bodies.
[2] Relative to Earth's surface, the geographic poles move by a few metres over periods of a few years. [ 3 ] This is a combination of Chandler wobble , a free oscillation with a period of about 433 days; an annual motion responding to seasonal movements of air and water masses; and an irregular drift towards the 80th west meridian . [ 4 ]
Quizlet was founded in October 2005 by Andrew Sutherland, who at the time was a 15-year old student, [2] and released to the public in January 2007. [3] Quizlet's primary products include digital flash cards, matching games, practice electronic assessments, and live quizzes. In 2017, 1 in 2 high school students used Quizlet. [4]
As the Earth has a sidereal rotation period of 23.93 hours, it has an angular velocity of 7.29 × 10 −5 rad·s −1. [2] The Earth has a moment of inertia, I = 8.04 × 10 37 kg·m 2. [3] Therefore, it has a rotational kinetic energy of 2.14 × 10 29 J. Part of the Earth's rotational energy can also be tapped using tidal power.
One complete orbit takes 365.256 days (1 sidereal year), during which time Earth has traveled 940 million km (584 million mi). [2] Ignoring the influence of other Solar System bodies, Earth's orbit, also called Earth's revolution, is an ellipse with the Earth–Sun barycenter as one focus with a current eccentricity of 0.0167. Since this value ...
The Earth rotation angle (ERA) measures the rotation of the Earth from an origin on the celestial equator, the Celestial Intermediate Origin, also termed the Celestial Ephemeris Origin, [9] that has no instantaneous motion along the equator; it was originally referred to as the non-rotating origin. This point is very close to the equinox of J2000.
The division of Earth by the Equator and the prime meridian Map roughly depicting the Eastern and Western hemispheres. In geography and cartography, hemispheres of Earth are any division of the globe into two equal halves (hemispheres), typically divided into northern and southern halves by the Equator and into western and eastern halves by the Prime meridian.
Eartha is the world's largest rotating and revolving globe, located within the former headquarters of the DeLorme mapping corporation in Yarmouth, Maine. [1] Garmin purchased the company and the building in 2016. [2] The globe weighs approximately 5,600 pounds (2,500 kg), and has a diameter of over 41 feet (12.5 m).