When the earth moves around the sun, Sun's position in relation to Earth changes with the change of every solar month (represented by a Sankranti). The sun describes seven great circles of latitude on the earth during 12 months of a year. These seven great circles of latitude described by the sun are known as the seven major chhandas. In this monograph, a humble effort has been made to reveal that not only the Vedas deal with the science of cosmology but their composition has also a scientific background. Through this monograph, readers will find that how do the syllable count of Vedic Metres and Musical notes used for chanting metres have a scientific basis.