Diameter of the Moon

The Physics Factbook
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Bibliographic Entry Result
(w/surrounding text)
Beichner, Robert J. and Serway, Ramond A. Physics for Scientists and Engineers with Modern Physics. Orlando, Florida: Saunders College Publishing, 2000.
Body Mass (kg) Mean Radius (m)
Moon 7.36 × 1022 1.74 × 106
3.48 × 106 m
Gorenstein, Paul. World Book- "Moon." Sydney, Australia: World Book Inc, 1992: 782-795. "The moon measures about 2160 miles (3476 km) across. The distance is about one fourth the diameter of the Earth, and 400 times smaller than that of the sun." 3.476 × 106 m
Arny, Thomas and Panindes, Nicholas A. Introductory Astronomy 2nd Edition. USA: Addison Wesley Publishing Company Inc, 1979: 115. "Solving for d in the proportion d/2πr = 0.5°/360°, gives us the moon's diameter -- about 2162 miles (3479 km)" 3.479 × 106 m
Moore, Patrick and Tirion, Wil. Cambridge Guide to Stars and Planets. United Kingdom: Reed International Books Limited, 1993: 23. "The moon is officially ranked as the Earth's satellite, but since it is relatively large and massive with a diameter of 3476 km and a mass of 0.012 that of the Earth, it may better be regarded as a companion planet." 3.476 × 106 m

The moon is Earth's nearest neighbor in space. Since ancient times, people have measured time by the phases of the moon, from new moon to new moon again (about 29½; days). However, people also thought the moon was a goddess or god (Luna and Diana were the "moon goddesses"), powerful enough to control humans and their actions. To this day, many countries use the moon to determine their months of the year through use of a lunar calendar.

The moon orbits the earth, and completes one rotation after 27 and a third days. The distance between the Earth and the Moon is 384,385 km. In comparison to the Earth however, the moon's weight and diameter are much smaller. The weight of the moon is 1/81 that of the Earth, and its diameter is ¼ of the Earth's. According to the data, the diameter of the moon is relatively centered, at about 3,479 km. This can be determined by a very simple proportion setting circumference equal to 360°, and the diameter of the moon equal to 0.5° (as this is how much of an angle the moon occupies):

(d/2πr) = 0.5°/360°
where r = 3.844 × 108 m, and d is the diameter of the moon
Solving for d gives 3.479 × 106 m

On the moon itself, no life exists, and there is no wind, air or water. While during the day, temperatures rise to over 173 °C and at night, temperatures drop way below freezing.

People have been fascinated by the moon ever since 1609, when Galileo formed a crude telescope to examine it. While as time progressed, drawings of the lunar surface improved, it was never fully explored. When the NASA space program began in 1958, space exploration became a reality. On July 20, 1969, Neil Armstrong became the first human being to land on the moon with Apollo 11 and explore it. Since then more information has been gathered on the moon (i.e., its density, formation, and effect on earth), and experiments on it are still being conducted to this day.

Samuel Bernard -- 2002

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