Whenever we look at the sky during the night time 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 color. This side never faces the earth and is visible only from space. But how did we come to know about the existence of the dark side of the moon?
In 1959, a Soviet space probe, Luna 3 was sent to space as a part of 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.
The next question which comes is why are we not able to see this side?
Well, we cannot see the dark side from 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 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.