I WAS TOO LAZY WHEN I THOUGHT OF ALL THIS...

WHY ARE THE ORBITS ELLIPTICAL AND NOT CIRCULAR?

The orbits in our solar system are not circular but elliptical. This has intrigued me so I Googled it. I found so many answers to this simple question. The best one I found goes here:

First of all, the sun is not the only thing that attracts the earth. We have huge planets like Jupiter and Saturn. If no other planets were present the orbit would have been circular. But according to the Newton's law of Gravitation, every particle which has a mass attracts every other particle which has mass. Therefore, the earths orbit would be distorted because of the presence of other planets like Jupiter, Saturn, Uranus etc.. So the circular orbit would become elliptical.

source: http://www.astro-tom.com/technical_data/elliptical_orbits.htm

So if the orbits in our solar system became elliptical because of gravity, how come the orbits in an atom are elliptical and  not circular? I did not find proper answers for this and I would invite some answers.

DOES THE EARTH NEVER STOP ROTATING?


I received really different answers for this, as varied as certainly Yes, and certainly No. So I would make my own explanation here combining all the answers.

It is unlikely for the earth to stop rotating completely but the earth does slow down a bit after a long period of time. one source said that the earth slows down by a second every century. But, forget how much time it slows down in what time, it is hard for the earth to stop rotating because it has too great a momentum to do so.  At any rate, according to the law of conservation of angular momentum, the earth does not "run out of" energy. It rotates as long as the sun does not become a Supernova.

source: http://www.newton.dep.anl.gov/askasci/ast99/ast99498.htm

So the question that arose here in my brain is:

WHY DOES THE EARTH ROTATE?

The earth rotates because simply it has not yet stopped moving. The solar system and indeed the Galaxy were formed by the condensation of a rotating mass of gas.

Conservation of angular momentum meant that any bodies formed from the gas would themselves be rotating. As frictional and other forces in space are very small the rotating bodies including the Earth slow only very gradually.
source: The Hindu Speaks on Scientific Facts, Volume II.