The Sun

The Sun is the star at the center of the Solar System. It gives energy in form of sunlight that provides light and supports almost all life on Earth by photosynthesis, it also drives Earth's climate and weather.

The Sun is by far the largest object in the Solar System. 98% of all matter within the Solar System is found within the Sun. This means that all the planets, moons, asteroids, minor planets, comets, gas, and dust would all combine to make up only 2% of all the matter in the Solar System.
Because the Sun is so large compared to everything else, it is easily able to hold on to the rest of the matter, causing everything else to orbit around it.

Source: http://happienews.blogspot.com/2009/03/its-sun-day-im-in-love-sung-to-tune-of.html