The other side

China’s Chang’e spacecraft has taken a photo of the Earth along with a view we don’t usually see, the other side of the moon.

OtherSideofMoon

EarthSky reported: Extraordinary shot of moon’s far side and Earth, from Chang’e

The Chinese Chang’e 5 test vehicle captured this extraordinary view of Earth over the far side of the moon on October 28, 2014. From Earth on this date, the phase of the moon was a waxing crescent. From the moon that day, the Earth was in a waning gibbous phase.

The Chinese Chang’e 5 spacecraft, which is testing lunar sample return technology, has rounded the lunar far side and is now on the return leg of its journey to the moon. It is landed back on Earth on Friday, October 31, 2014.

Moon Connection explains Why Do We Only See One Side of the Moon?

The same physical half of the Moon, the “near side”, is always facing Earth. That means there is a far side or so-called “dark side” that is never facing Earth and can only be seen from space. This is true regardless of the moon phase.

Why is this the case? We all know that the Earth rotates on its own axis, so theoretically, the Moon should also do the same, allowing us to get a full picture of the planetoid. Why are we limited to seeing only 50 percent? It turns out that the speed at which the Moon rotates has led to this particular phenomenon. Millions of years ago, the Moon spun at a much faster pace than it does now. However, the gravitational influence of the Earth has gradually acted upon the Moon to slow its rotation down, in the same way that the much smaller gravitational influence of the Moon acts upon the Earth to create tides. This influence slowed the rotational period of the Moon to match that of its orbit – about 29.5 days – and it is now “locked in” to this period.

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.

We can actually see more than half the moon due to a ‘rocking’ motion.

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 rotational speed of the Moon is constant however – and this difference between orbital speed and rotational speed means that when the Moon is farthest from the Earth, its orbital speed slows down just enough to allow its rotational speed to overtake it, giving observers a small glimpse of the usually hidden area. 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).

There is no dark side of the moon, only a side we can’t see from Earth.

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. In fact, since the Moon is constantly rotating on its own axis, there is no area of the planetoid which is in permanent darkness, and the far side of the Moon is only completely devoid of sunlight during a Full Moon – when the Sun is facing the Moon with the Earth in between.

What’s this got to do with politics? Nothing really, but I’ll make up an association.

There’s another side to most things, even though we may not find it easy to see it.

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1 Comment

  1. kathy maddren

     /  10th November 2014

    I see your association Pee-Gee.

    And I’m prepared to raise you one more.

    This post beats all Pete Belts boring maps hands down, and even given “Lux” a good run for his or her money.

    Reply

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