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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.
Equatorial mounts allow astronomers to point telescopes at the same celestial object for longer times while compensating for Earth's rotation in an easy way. The axis of an equatorial mount is parallel to Earth's surface when observing stars at Earth's equator – but perpendicular to it when observing from one of Earth's poles.
It uses a cantilever mount with two motors, and simulates one day's revolution and rotation every 18 minutes, though it is possible for the motors to fully rotate the globe in as little as one minute. [citation needed] The truss structure of the globe made visible during a panel-replacement project in 2023
where latitudes north and south of the equator are defined as positive and negative, respectively. A "pendulum day" is the time needed for the plane of a freely suspended Foucault pendulum to complete an apparent rotation about the local vertical. This is one sidereal day divided by the sine of the latitude.
Political map of Europe, showing south at the top. Research suggests that north-south positions on maps have psychological consequences. In general, north is associated with richer people, more expensive real estate, and higher altitude, while south is associated with poorer people, cheaper prices, and lower altitude (the "north-south bias").
The x-axis is permanently fixed in a direction relative to the celestial sphere, which does not rotate as Earth does. The z-axis lies at a 90° angle to the equatorial plane and extends through the North Pole. Due to forces that the Sun and Moon exert, Earth's equatorial plane moves with respect to the celestial sphere.
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The Earth's rotation rate is still slowing down, though gradually, by about two thousandths of a second per rotation every 100 years. [1] Estimates of how fast the Earth was rotating in the past vary, because it is not known exactly how the moon was formed. Estimates of the Earth's rotation 500 million years ago are around 20 modern hours per ...