People often say “the dark side of the moon” while referring to the lunar face that can’t be seen from the earth. However, the phrase is used incorrectly. Assuming that one isn’t talking about the Pink Floyd’s famous album , it always refers to the far side of the moon, which despite pointing away from the earth sees as much sunlight as the side facing the earth. So the dark side of the moon isn’t actually dark. The reason why it exists is because of a physics phenomenon known as the tidal locking. In the next few sections, we will be getting into more details about it.
What is the Dark Side of the Moon?
Whenever we look at the sky in the night to see the moon, it appears the same every time. No matter how we see the moon or from where we see the moon, it always seems to feature the same landscape. The side of the moon which we are never able to see being on earth is known as the ‘dark side of the moon.’ It will be wrong to say that this side which is considered as the dark side of the moon is dark in colour. This side never faces the earth and is visible only from space.
Dark Side of the Moon Discovery
In 1959, a Soviet space probe, Luna 3 was sent to space as a part of the Luna program. It sent back the images of the moon which were never seen by the people on the earth. These images were of the dark side of the moon which is never visible to us.
Why can’t we see the dark side of the moon?
Well, we cannot see the dark side of the earth because the moon is tidally locked to the earth. The earth rotates on its axis continuously and so does the moon. The time required by the Moon to rotate about its axis exactly matches to the time needed for orbiting the earth since earth and moon are tidally locked. In simple words, the rotational period and the orbital period of the moon is the same. Therefore, we can see only one side of the moon. In other words, we can say that due to the sync in rotation and revolution of earth and moon, only one side of the moon always faces the earth, thereby another side which is never seen by us is called the dark side.
What is the temperature on the moon?
The temperature on the moon is extreme from boiling hot to chilling cold which is dependent on the sun’s position. When the sunlight reaches the surface of the moon, the temperature is 127℃ and when the sun goes down, the temperature is -173℃. On the moon, day time lasts for 13.5 days and night time lasts for 13 days.
Different Phases of the Moon
There are 8 phases of the moon and they are:
- New moon: This is the first phase of the moon when the moon is between the sun and the earth. During this phase the moon is not seen as the dark side of the moon is facing the earth.
- Waxing crescent: This is the second phase which occurs after a few days of the new moon. During this phase, the moon travels towards the east. There are times when rest of the moon is visible due to the phenomenon known as “earthshine” where the reflects sunlight to the moon.
- First quarter: This is the third phase during which people may see either right half of the illuminated moon or the left half of the illuminated moon depending on the location. The moon completes the 1/4th of the lunar phase.
- Waxing gibbous moon: This is the fourth phase where the waxing means growing large and gibbous means shape, thus the “growing shape”.
- Full moon: This is the fifth phase of the moon when the sun and the moon are on the opposite side of the earth. When the moon is at its closest point to the earth, it is known as “supermoon” and when it is at the farthest point from the earth, it is known as “micro-moon”.
- Waning gibbous moon: This is the sixth phase of the moon and waning means decreasing, so it is known as a decrease in shape which lasts until the moon is half illuminated.
- Third quarter moon: This is the seventh phase of the moon and the moon has completed 3/4th of the lunar phase.
- Waning crescent moon: This is the last phase of the moon and during this phase too “earthshine” is seen. This phase will end when both the sun and the moon rise at the same time giving rise to a new lunar cycle.
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