The Sun

    I think the sun is a very cool & interesting thing. The sun is a star and it is by far the largest object in the solar system. The Greeks called it Helios and the Romans called it Sol. The sun is about 70% hydrogen, 28% helium by mass everything else amounts to 2%. This changes slowly over time as the Sun converts hydrogen to helium in its core. The outer layers of the sun exhibit differential rotation: at the equator the surface rotates once every 25.4 days; near the poles it's as much as 36 days. This happens because the sun is not a solid body like the Earth. The differential rotation extends considerably own into the interior of the Sun but the core of the Sun rotates as a solid body. The temperature of the Sun is 15.6 million Kelvin and the pressure is 250 billion atmospheres. At the center of the core, the Sun's density is more than 150 times that of water. http://nineplanets.org/sol.html