Why do we see 59 of the moon

Earth orbits the Sun once every days a year and spins on its axis once every 24 hours a day. The Moon orbits Earth once every This means that although the Moon is rotating, it always keeps one face toward us.

All of the manned space missions to the Moon have landed on the nearside due to communication needs, so humans have physically explored this side much more. We have remotely explored both sides of the Moon with orbiting satellites. Since then, many satellites have sent back pictures and other data showing that the farside of the Moon differs from the nearside. Mare deposits of dark basalt fill many large basins on the nearside, whereas the highlands of the farside are made from a light-colored mineral called feldspar.

This may result from even another difference: The lunar crust is thinner on the nearside, which means that the mantle the once molten, denser layer that underlies the crust is closer to the surface there. Asteroid impacts could more easily fracture the crust down to the level of the mantle on the nearside, allowing magma to rise up to fill impact basins and form mare deposits. Snapshot : ALMA spots moon-forming disk around distant exoplanet. Ask Astro : Does dark energy create the voids between galaxy clusters?

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If the Moon didn't spin at all, then eventually it would show its far side to the Earth while moving around our planet in orbit. However, since the rotational period is exactly the same as the orbital period, the same portion of the Moon's sphere is always facing the Earth.

Another interesting fact is that actually a little bit more than half of the Moon's surface is observable from Earth. Since the Moon's orbit is elliptical, and not circular, the speed of its orbital travel increases and decreases depending on how close it is to our planet. The term for this "rocking" motion of the Moon is called libration and it allows for 59 percent of the Moon to be seen in total over time.

Finally, one reason that the far side of the Moon is frequently referred to as the "dark side" is because many people mistakenly think that it never sees any light from the Sun. In that sense the term "dark side" is wrong and misleading. All Rights Reserved. Astrological Moon Sign.