The Central Powerhouse
The Sun, the central powerhouse of our solar system. A medium size, yellow star, composed principally of hydrogen - the lightest chemical element in the universe. Through a process of nuclear fusion - the union of atoms, the Sun forms denser atoms, releasing energy and heat in the process. This energy and heat radiates out, in all directions through the vacuum of space. All the planets in our solar system, intercept a small amount of this energy and heat, as they rotate around their axises and orbit around the Sun. The energy travels at the universal speed limit - known as the speed-of-light (c): which is approximately 3 x108 metres per second. Earth is just under 150 million kilometres from the Sun, and so it takes 8.3 minutes for energy leaving the Sun's surface to reach Earth's atmosphere.
To find out more about how energy, light, and heat is generated in the Sun, and what the resulting light, energy, and heat actually is, then dive into the blog posts below. The chronological order also has some sense in the order of understanding: starting off with simpler concepts at the beginning (at the bottom of the page), and becoming more complex as time goes on (near the top).