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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.
In astronomy, the rotation period or spin period [1] of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the sidereal rotation period (or sidereal day), i.e., the time that the object takes to complete a full rotation around its axis relative to the background stars (inertial space).
A size comparison of Neptune and Earth. Neptune's mass of 1.0243 × 10 26 kg [8] is intermediate between Earth and the larger gas giants: it is 17 times that of Earth but just 1/19th that of Jupiter. [g] Its gravity at 1 bar is 11.15 m/s 2, 1.14 times the surface gravity of Earth, [71] and surpassed only by Jupiter. [72]
The best time to see the planetary parade in January is during the first couple of hours after the Sun goes down, with Saturn and Venus appearing close to each other in the southwest, Jupiter high ...
The slightly longer stellar period is measured as the Earth rotation angle (ERA), formerly the stellar angle. [4] An increase of 360° in the ERA is a full rotation of the Earth. A sidereal day on Earth is approximately 86164.0905 seconds (23 h 56 min 4.0905 s or 23.9344696 h).
Earth has a new “mini-moon” after an asteroid has joined our orbit.. The object, known as 2024 PT5, has been chasing after us for years. Now, it has become close enough to be pulled in by our ...
An ancient green comet not seen since Neanderthals roamed the Earth will make its closest approach to the sun since the last ice age tonight. ... channel starting at 9 p.m. Mountain time/ 8 p.m ...
The time until Betelgeuse explodes depends on the predicted initial conditions and on the estimate of the time already spent as a red supergiant. The total lifetime from the start of the red supergiant phase to core collapse varies from about 300,000 years for a rotating 25 M ☉ star, 550,000 years for a rotating 20 M ☉ star, and up to a ...