座右铭 发表于 2025-3-26 22:37:42
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Planetary Orbits,c. Cometary orbits, by contrast, are distributed at random in space and have very varied shapes. The near-circular orbits of the planets are so widely separated that they never come close to one another.释放 发表于 2025-3-27 06:55:49
Physical Ephemerides of the Planets,anets, the Sun, or the Moon, is also interested in data that describe the aspect of the various bodies. The visual magnitude and the apparent angular diameter are data of fundamental importance. Anyone who wants to observe and plot surface markings or atmospheric structure also needs to know the ori泥瓦匠 发表于 2025-3-27 13:20:18
The Orbit of the Moon,e find that it is not its nearest neighbour, the Earth, that has the greatest effect, but the more distant Sun. Although gravitational force decreases as the square of the distance, the Sun’s gravity exceeds that of the Earth, because of its far greater mass.aqueduct 发表于 2025-3-27 16:52:47
Solar Eclipses,iptic would then see the Sun, Moon and Earth in a straight line. Despite this, the shadow cast by the Moon rarely touches the Earth. Because of the inclination of its orbit, at the time of New Moon the Moon is usually above or below the Earth’s orbital plane, so its shadow misses the Earth. The Moon知道 发表于 2025-3-27 19:04:28
Stellar Occultations,akes it close to bright stars. It is particularly striking when a stellar occultation occurs: a star suddenly vanishes behind the eastern limb of the Moon, and then reappears on the other side after a certain interval. In total, there are about one thousand stars visible to the naked eye that the MoIsthmus 发表于 2025-3-27 21:58:09
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M. K. Walz,D. Kröpfl,K.-A. Walz,F.-W. Eiglercension and declination) or to the ecliptic (ecliptic longitude and latitude). On the other hand, the distance cannot be measured, so knowledge of it cannot be used in orbit determination. To derive six orbital elements, the same number of independent observational values are required, so three observations must be available.步履蹒跚 发表于 2025-3-28 14:06:37
how long the routine analysis of data took with pencil, paper, and logarithmic tables. Thus when Wilhelm Olbers discovered the minor planet Vesta in 1807 and gathered the necessary observations, his friend Gauss needed almost 10 hours to hand calculate its orbit. That achievement astonished many le