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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 ).
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]
Given the different Sun incidence in different positions in the orbit, it is necessary to define a standard point of the orbit of the planet, to define the planet position in the orbit at each moment of the year w.r.t such point; this point is called with several names: vernal equinox, spring equinox, March equinox, all equivalent, and named considering northern hemisphere seasons.
Detailed analysis of data from the Cassini spacecraft gives a value of the moment of inertia of Saturn that is just outside the range for the resonance to exist, meaning that the spin axis does not stay in phase with Neptune's orbital inclination in the long term, as it apparently did in the past. One theory for why the resonance came to an end ...
Mars comes closer to Earth more than any other planet save Venus at its nearest—56 million km is the closest distance between Mars and Earth, whereas the closest Venus comes to Earth is 40 million km. Mars comes closest to Earth every other year, around the time of its opposition, when Earth is sweeping between the Sun and Mars. Extra-close ...
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.
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.
Here's everything to know about the Mars rock samples, potential plans to get them to Earth and what's next for Perseverance: The year ahead in space travel: Uncrewed lunar missions and 1st ...