Moon Facts

Location in the Solar System:

  • Earth’s only moon
  • Fifth largest moon in the solar system
    • but the largest and most massive moon in the Solar System relative to its parent planet
    • it’s even larger than Pluto
  • Equatorial radius of 1080 miles
  • Less than a 3rd the width of Earth
  • An average distance from Earth of 238,855 miles away
    • this distance will vary from 221,829 to 252,898 miles over the course of a year
    • that distance is about 30 times the diameter of the Earth
    • Getting 1 inch further away from Earth each year

LunaServ GIS Map Tool

Orbit:

  • elliptical orbit
  • Rotates at same rate that it revolves around Earth. So, same hemisphere always faces Earth all of the time
    • this is known as synchronous rotation
  • As a result, we never see the far side (or “dark side”) of the Moon from the surface of the Earth
  • Moon makes a complete orbit of the Earth in 27 days
  • It appears to orbit us every 29.5 days, trick due to the fact that we are moving as well, rotating on our axis, and orbiting the Sun

Composition:

  • solid iron-rich core is 149 miles in radius
  • surrounded by a liquid iron shell 56 miles thick
  • A partially molten layer 93 miles thick surrounds iron core
  • Mantle extends from top of partially molten layer to the bottom of Moon’s crust
  • Most likely made of minerals like olivine and pyroxene (made up of magnesium, iron, silicon, and oxygen atoms)
  • Crust has a thickness of about 43 miles on Moon’s near side and 93 miles on far side
  • Made up of oxygen, silicon, magnesium, iron, calcium, aluminum
  • Small amounts of titanium, uranium, thorium, potassium, and hydrogen

Surface:

  • Steady rain of asteroids and meteoroids has left many craters
  • Tycho Crater is more than 52 miles wide
  • Over billions of years, these impacts have ground the surface of the Moon into fragments ranging from boulders to powder (called the lunar regolith)
  • Beneath the powder is a region of fractured bedrock called megaregolith
  • Light areas of moon known as the highlands
  • Dark areas called Maria (latin for sea). These are impact basins filled w/ lava between 4.2 and 1.2 billion years ago
  • These light and dark areas represent rocks of different composition and ages, which provides evidence for how early crust may have crystallized from a lunar magma ocean
  • Gravity on the surface of the Moon is about 1/6 of Earth
  • Temperature range:
    • 260 degrees F when in full sun
    • -280 degrees in darkness

Water:

  • Although initially thought to be without water, large concentrations of frozen water in the shadowed regions of the north and south poles of the Moon.
  • Meteor impacts also releases sub-surface lunar water, most of which is ejected into space

Atmosphere

  • very thin and weak atmosphere, called exosphere
  • Does not provide any protection from sun’s radiation or from meteoroids

Magnetosphere

  • early moon may have developed an internal dynamo (mechanism for generating global magnetic fields), but today has a very weak magnetic field (thousands of times weaker than Earth’s)

Sources: [^ https://science.nasa.gov/moon/facts/] [^ https://en.wikipedia.org/wiki/Moon] [^ https://nssdc.gsfc.nasa.gov/planetary/factsheet/moonfact.html]