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The superior planets, orbiting outside the Earth's orbit, do not exhibit a full range of phases since their maximum phase angles are smaller than 90°. Mars often appears significantly gibbous, it has a maximum phase angle of 45°. Jupiter has a maximum phase angle of 11.1° and Saturn of 6°, [1] so their phases are almost always full.
Jupiter and Saturn have several large moons, such as Io, Europa, Ganymede and Titan, which may have originated from discs around each giant planet in much the same way that the planets formed from the disc around the Sun. [88] [89] [90] This origin is indicated by the large sizes of the moons and their proximity to the planet. These attributes ...
Planet orbiting the Sun in a circular orbit (e=0.0) Planet orbiting the Sun in an orbit with e=0.5 Planet orbiting the Sun in an orbit with e=0.2 Planet orbiting the Sun in an orbit with e=0.8 The red ray rotates at a constant angular velocity and with the same orbital time period as the planet, =.
On a prograde planet like the Earth, the sidereal day is shorter than the solar day. At time 1, the Sun and a certain distant star are both overhead. At time 2, the planet has rotated 360° and the distant star is overhead again (1→2 = one sidereal day). But it is not until a little later, at time 3, that the Sun is overhead again (1→3 = one solar day). More simply, 1→2 is a complete ...
If the Sun–Neptune distance is scaled to 100 metres (330 ft), then the Sun would be about 3 cm (1.2 in) in diameter (roughly two-thirds the diameter of a golf ball), the giant planets would be all smaller than about 3 mm (0.12 in), and Earth's diameter along with that of the other terrestrial planets would be smaller than a flea (0.3 mm or 0. ...
up to one Sun or Moon diameter (about 0.5° or 30') every 2 minutes; up to one diameter of the planet Venus in inferior conjunction (about 1' or 60") about every 4 seconds; 2,000 diameters of the largest stars per second; Star trail and time-lapse photography capture diurnal motion blur. The apparent motion of stars near the celestial pole ...
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.
After waiting for most of the day, he eventually saw the transit when clouds obscuring the Sun cleared at about 15:15, half an hour before sunset. His observations allowed him to make a well-informed guess for the diameter of Venus and an estimate of the mean distance between the Earth and the Sun (59.4 million mi (95.6 million km; 0.639 AU)).