This question has interested the scientists throughout history from the earliest times. In the 6th century B.C The Greek philosopher mathematician Pythagoras had said that the earth is round which was not accepted by many at that time.The Indian astronomer Aryabhata-I (476- 550 A.D) had written in his treatise Aryabhatia that the earth was like a sphere and spinning on its axis .The fact that the earth is spherical was confirmed when the earth was viewed from outer space. According to the astronauts the earth appears as a blue sphere with green and brown patches. On July 19, 2013 NASA 'Distant spacecraft “Cassini" had sent pictures of the earth and the moon as seen from the Saturn, which is nearly 800 billion km away. In the Cassini images Earth and the moon appear as mere dots. The earth a pale blue and the moon a stark white, are visible between Saturn's rings. The earth is spherical but not exactly a sphere. It is slightly bulged at the equator and flattened at the poles. The shape of the earth is called an Oblate Spheroid.