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5 godz. temu · One astronomical unit (about 150 million kilometres; 93 million miles) is defined as the mean distance between the centres of the Sun and the Earth. The instantaneous distance varies by about ± 2.5 million km or 1.55 million miles as Earth moves from perihelion on ~ January 3rd to aphelion on ~ July 4th.
1 dzień temu · The centimetre ( SI symbol: cm) is a unit of length in the metric system equal to 10−2 metres ( 1 100 m = 0.01 m ). To help compare different orders of magnitude, this section lists lengths between 10 −2 m and 10 −1 m (1 cm and 1 dm). 1 cm – 10 millimetres. 1 cm – 0.39 inches. 1 cm – edge of a square of area 1 cm 2.
5 godz. temu · The Moon is Earth's only natural satellite.It orbits at an average distance of 384,400 km (238,900 mi), about 30 times the diameter of Earth. Tidal forces between Earth and the Moon have over time synchronized the Moon's orbital period (lunar month) with its rotation period at 29.5 Earth days, causing the same side of the Moon to always face Earth. . The Moon's gravitational pull – and to a ...
5 godz. temu · After invention of spectroheliographs and monochromatic filters, flares began to be observed much more often in Hα and some other chromospheric spectral lines.An Hα monochromatic image of a flare often shows two bright ribbons, the distance between which increases with time (Fig. 10.2).The area of emitting regions is from several millionths to several thousandths of the solar hemispheres.
