The Physics
Factbook
An encyclopedia of scientific essays

# Mass of the Moon

Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Spaulding, N.E.; Namowitz, S.N. Heath. Earth Science. Massachusetts, DC Heath and Company, 1994. "The moon's density, about 3.3g/cm3 is less than Earth's and it's mass is only about one eightieth Earth's." 7.475 × 1022 kg
New Book of Knowledge, Connecticut, Grolier Inc., 2001. "Mass: 74 quitillion tons about 1/81 the mass of Earth." 7.383 × 1022 kg
"The Moon." Time Life Space and Planets. "Only one fourth of the diameter of Earth with just 1.25 percent of its mass, the Moon is a captive of Earth's gravitational force." 7.475 × 1022 kg
The Moon. Nine Planets. University of Arizona. "mass: 7.35 e22 kg" 7.35 × 1022kg
Moon. Nasa Solar System Exploration. "Mass: 7.3483 e 25 g" 7.34 × 1022 kg

Scientists still argue about how the moon came into existence. Some say that it formed with the Earth and then broke off after colliding with another body. Others say that it was captured by Earth's gravitation. The moon is Earth's satellite, and one of the only satellites which is the closest in size to the planet that it orbits.

The moon has a diameter of 3476 km and orbits the earth at a distance of 384,400 km at a speed of 3600 km/hr. The moon has 8 different phases within its period which lasts 29.5 days. Ocean tides are an effect of the gravitational forces between the Earth and the moon. The moon has no global magnetic field and no atmosphere. It's gravity is about a sixth of the Earth's making it easier to launch a spacecraft from the moon. The moon's layered structure (the crust, mantle, molten zone and core) was developed from recordings of moonquakes. The moon's surface is composed mainly of craters.

In calculating the results, the mass of the Earth used was 5.98 × 1024 kg.

Bibliographic Entry Result
(w/surrounding text)
Standardized
Result
Hewitt, Paul G. Conceptual Physics. Addison-Wesley, 1987: Table B-1. "Mass of the Earth = 5.98 × 1024 kg"
"Mass of the moon = 7.36 × 1022 kg"
7.36 × 1022 kg
Lide, David R. Handbook of Chemistry and Physics 81st edition. 2000-2001: 14-3.
 Planet Mass 1024 kg Earth 5.9742 Moon 0.073483
7.3483 × 1022 kg
Moore, Patrick & Tirion, Wil. Cambridge Guide to Stars and Planets. Reed International, 1993: 25. "The moon has one-quarter the diameter and 0.012 the mass of the Earth." 7.2 × 1022 kg
Giancoli, Douglas C. Physics: Principles with Applications., 1980: inside front cover. "Moon: Mass 7.4 × 1022 kg" 7.4 × 1022 kg
McGraw Hill Encyclopedia of Science and Technology. McGraw Hill, vol. 11. 418. "Mass 1/81.301 Earth's mass, or 1.6 × 1023 lb (7348 × 1022 kg)" 7.348 × 1022 kg

The moon is the only natural satellite of the Earth. The moon takes about 27 days, 7 hours, and 43 minutes to complete one revolution of its elliptical orbit around the Earth. The moon is 384,400 km (238,857 miles) away from the Earth. It moves around the Earth at an average speed of 3700 km/h (2300 mph). Luna, better known as the moon, is only one-fourth the size of the Earth, having a diameter of 3,476 km (2,318 miles); which is less than the distance across the United States. The volume of the moon is about 1/50 of the Earth. The Earth and its moon could be considered twin planets compared to huge planet like Jupiter and Saturn, which are 40 or 50 times larger than their biggest moons. The moon's mass is about 0.012 times that of the Earth (7.35 × 1022 kg). The moon's gravity is one-sixth that of the Earth. This explains why astronauts are unable to walk on the moon as they do on the Earth.

The origin of the Moon is uncertain, but the leading theory that explains the origin of the moon is known as "planetessimal impact." According to this theory, a "Mars-sized" body hit Earth and the moon resulted from the debris of both that body and Earth. Since the moon has no atmosphere or clouds, the components in the solids of the moon do not weather chemically as they would have with the presence of an atmosphere. Due to this fact, scientists believe the moon is approximately 4.5 billion years based on the oldest lunar rocks found.

The moon has played an important role in the Earth's development over billions of years. Earth's wobble is stabilized by the presence of the moon, which has led to a more stable climate over long periods of time. This may have affected the course of the development and growth of life on Earth.

As of today there have been 71 missions to the moon, 12 people have landed on the moon, and in 1998 the Lunar Prospector spacecraft reported finding water ice on the moon's surface.