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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 ).
Earth rotates once in about 24 hours with respect to the Sun, but once every 23 hours, 56 minutes and 4 seconds with respect to other distant stars . Earth's rotation is slowing slightly with time; thus, a day was shorter in the past. This is due to the tidal effects the Moon has on Earth's rotation.
The length of a day on Uranus as measured by Voyager 2 is 17 hours, 14 minutes. [49] Uranus was shown to have a magnetic field that was misaligned with its rotational axis, unlike other planets that had been visited to that point, [50] [53] and a helix-shaped magnetic tail stretching 10 million kilometers (6 million miles) away from the Sun. [50]
How did Uranus get its name? English astronomer William Herschel discovered the ice giant in 1781 and tried unsuccessfully to name it after King George III, according to NASA.
The pronunciation of the name Uranus preferred among astronomers is / ˈ jʊər ə n ə s / YOOR-ə-nəs, [1] with the long "u" of English and stress on the first syllable as in Latin Uranus, in contrast to / j ʊ ˈ r eɪ n ə s / yoo-RAY-nəs, with stress on the second syllable and a long a, though both are considered acceptable. [g]
Earth makes one rotation around its axis each sidereal day; during that time it moves a short distance (about 1°) along its orbit around the Sun. So after a sidereal day has passed, Earth still needs to rotate slightly more before the Sun reaches local noon according to solar time.
Scientists have published two studies on the historic cache of lunar soil samples from the moon’s far side that China’s Chang’e-6 mission brought back to Earth in June.
A synodic day (or synodic rotation period or solar day) is the period for a celestial object to rotate once in relation to the star it is orbiting, and is the basis of solar time. The synodic day is distinguished from the sidereal day, which is one complete rotation in relation to distant stars [1] and is the basis of sidereal time.