Question

Why is the earth in elliptical shape?

Answer 1

The elliptical nature of Earth's orbit is due entirely to the original force which tossed it away from the solar disc (now the sun). If the momentum of this toss had been greater, the Earth's orbit would have been more highly elliptical, or it might have been tossed completely out of the solar system forever. If it had been a slightly less violent toss, Earth's orbit might have been perfectly circular (and it really is very close to being circular) or if it had been even less violent, it might have spiralled right back into the disc and never become a planet at all. The sun is the biggest source of gravity in our solar system. The gravitational force of the sun pulls objects straight to it because the planets are in motion.