0One of the areas of physics in which measurement has been bewildering is astronomy. How far away are the stars? How large is the universe?
These are the most fundamental and profound questions. One can trace the evolution of astronomy through the changing techniques of calculating stellar distances. Untill the end of nineteenth century, the only way astronomers could make these calculations was by measuring parallax.
You are familiar with the phenomenon of parallax without even realizing it. Wherever you are sitting, look around and find a stretch of wall with some sort of feature along it- a doorway or a picture hanging on it. Now stretch your hand straight out in front of you and raise a finger so that it is to one side or the other side of the feature. Now first close your right eye and then close your left eye. You will see that your finger jumped from left to right relative to the feature. If you move your finger closer the movement will be more. This effect is parallax. It happens because of the switch to different line of sight in observing an object.
Be in touch to know how this phenomenon is used to calculate astronomical distances.
