Moon Facts



  • 4.5 billion years old created as a result of asteroid bombardment of the Earth’s surface.
  • Takes 27.3 days to rotate on its axis.
  • It takes the Moon 29.3 days to orbit the Earth. During this time it makes a complete turn on its axis. As a result the same side of the is always seen.
  • The relative movement between The Moon, Earth and Sun result in that a little more than one half of The Moon is visible allowing us to see slightly different views of the edges at different stages in its orbit. This is called liberation. (Note for example Mare Crisium position as it appears at times on the edge and at other times more central, revealing about 18% more of the dark side of the Moon)
  • Lunar libration reveals 59% of the moon’s surface. You can see only 50% of the lunar disk at any one time. Even so, lunar libration – the slight north-south rocking and east-west wobbling of the moon – enables acute observers to peek at a tiny portion of the moon’s back side. Over time, it’s possible to see as much as 59% of the lunar disk.
  • The different phases of the Moon reveals differing detail in the lunar surface as the shadow line or terminator changes position. The rest of the Moon is highly illuminated but this changing region under a low angle of illumination will reveal continuously differing detail throughout the month.
  • The Moon has a nearly circular orbit which is tilted about 5° to the plane of the Earth’s orbit. Its average distance from the Earth is 384,400 km. The combination of the Moon’s size and its distance from the Earth causes the Moon to appear the same size in the sky as the Sun, which is one reason we can have total solar eclipses.
  • Earthshine is the faint glow of the non -illuminated part of the Moon due to reflected sunlight off the surface of the Earth which can be seen with the naked eye.
  • The changing position of the Moon with respect to the Sun leads to lunar phases.
Observation Of The Moon With Binoculars
 Celestron Bin
The simplest way to view the Moon is by using binoculars.  (The average pair of binoculars would be of the same magnification or resolving power of a 200mm camera lens) The higher the power or magnification the more it will be difficult to keep your hands steady enough for viewing. A solution to this would be to mount them on a tripod or use image -stabilized binoculars. Observing by this method will allow you to see numerous lunar features such as the visible ‘dark blotches’ called maria as Maria Serenitatis (674 km diameter) and Tranquillitatis (873 km diameter) formed by asteroids 3.5 million years ago and the larger craters such as Copernicus (93 km diameter) and Tyco (86 km in diameter) with its white radiating rays which was formed 2.5 million years ago.
Moon maps not overly detailed and just right for the use with binoculars can be found at Eyes On The Sky


Astronomy Notebook
The Moon
Images And Videos
Equipment and Setup
Notes on Equipment