synonymDiurnal visual movement(Sunday visual sports) generally refers to Sunday sports
The diurnal movement, also known as the diurnal apparent movement, describes the apparent apparent movement of the celestial bodies in the sky observed by observers on the earth every day, especially in the near polar region.This is due to the rotation of the Earth around the axis, making all celestial bodies move in circles around this axis (from the observer's eyes, it is around the Polaris). This circle is called the circle of the day, and it takes 23 hours, 56 minutes, 4.09 seconds to complete a circle of motion (that is, a whole star day).The rise and fall of the sun and the moon in the east is also the embodiment of the Sunday movement.
(Low latitude to high latitude area between pole and equator)
When facing north, the celestial body whose height is lower than Polaris moves from left to right, that is, from west to east (visually, it sweeps between Polaris and the horizon).
When facing north, the celestial body whose height is higher than Polaris moves from right to left, that is, from east to west.
When facing south, all the celestial bodies move from left to right, that is, from east to west.
Therefore, in the vicinity of PolarisArched polar starThe visual movement is counterclockwise.According to the above example, the north facing observer observed that the stars that never fall below the horizon at the north celestial pole formed a circle in the night sky (taking Polaris or the south celestial pole as the center, and the horizon height of the observer's geographical latitude value as the radius), which is called the constant display circle. For details, seecelestial sphereEntry.
North Pole
At the North Pole, because the north is at the zenith when the observer is standing on the ground (meaning that the observer's earth axis overlaps), the east, south and west are meaningless. Celestial objects only move from left to right. If you look vertically up near the zenith, all celestial objects move counterclockwise.
southern hemisphere
In the southern hemisphere, the relationship between north and south and between left and right is reversed. The east-west direction has not changed, and the Polaris is replaced by the South Pole (because there is no bright star in the southern celestial pole).The polar arch near the pole moves clockwise.
equator
At the equator, the south and north celestial poles are close to the horizon. When the observer faces north, the stars near the north celestial pole rotate counterclockwise (to the left). When the observer faces south, the stars near the south celestial pole rotate clockwise (to the right).In addition to the observation at two poles, all apparent motion directions of celestial bodies observed at other places are from east to west.
Calculation of moving path
The length of the daily apparent motion path of the celestial body on the celestial sphere, including the part that may be below the horizon, corresponds to the cosine of the geographical latitude.Therefore, the daily motion speed of the celestial body is a cosine function, moving 15 ° per hour, 15 'per minute, 15 "per second (measured by angular diameter):
Move the diameter of the moon or sun every two minutes.
Move the maximum diameter of the planet for about 4 seconds.
It moves 2000 times the diameter of the largest star every second.
Shooting method
Announce
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The phenomenon of diurnal movement can be seen by prolonging the exposure time of photography. The stars near the poles move slowly on the arc next to the poles.The camera installed on the equatorial instrument can reverse the movement of right ascension and cancel the diurnal apparent movement to track celestial photography as long as the correct geographical latitude is adjusted (that is, aligned with the northern celestial pole);The telescope can also use an equatorial instrument with an automatic tracking system attached to a driving motor to track celestial bodies for observing and photographing celestial bodies.
