When observing closely, the night sky would not be the same every night. Instead of the stars and constellations visible tonight, a different set of stars and constellations will be visible in a few months due to the rotation & revolution of the Earth.

Star maps could be used to identify stars and constellations in the night sky. Following are twelve pairs of maps relevant to the 15th day of each month at 4.00 a.m. and 8.00 p.m. prepared for Sri Lankan locality.