Our PlanetScience

Why does the sun shine?


Have you ever learned about why stars shine? Stars are made up of clouds of dust and gas in outer-space that spin around and are pulled inward by gravity. As the mixture of dust and gas compresses, it gets hotter and hotter until a special reaction occurs and some of the gas particles join together to become bigger particles! This process creates energy deep in the center of a star, and it's that energy which gives a star its heat and shining light!

Sound like anything else you know?

If you think a hot, shining mass of energy also sounds a whole lot like the sun, then you're right! The sun, believe it or not, is a star too! And just like other stars shine because of all their energy, so does the sun!

However, you've probably noticed that the sun's heat and light is different than that of other stars to those of us here on Earth. The sun's light probably seems much brighter than other stars, and much hotter too! The reason we're affected so differently by the sun's energy is because we're much closer to the sun! The sun is about 150 million kilometers away from Earth. That's no short distance, but it's closer than the next nearest star (in a group named Alpha Centauri), which is over four light years away! (That's over 40 trillion kilometers more than 260,000 times farther than the sun!)

Having the sun's light and warmth is very important to a lot of things on Earth. For example, plants rely on sunlight for helping them to make food, which makes it possible for us to have food too when we eat the plants! The heat from the light of the sun is also responsible for keeping the Earth warm, so that we're able to live on it! Having sunlight also gives us a daytime for being awake, and a nighttime for going to sleep!!


Fun in the sun!

On a sunny day, go outside in the morning and look up at the sky. Be careful not to look right into the sun, as it might hurt your eyes a little bit, but try to notice where in the sky the sun is. Go back outside and look up at the sky again in the middle of the day. Is the sun still in the same spot as it was in the morning, or has it moved? Try this again at the end of the day, right before the sun is going to set. Notice anything interesting??

Further Information

Hot, hot, hot! The surface of the sun is about 5,500 degrees Celsius or 9,940 degrees Fahrenheit! To understand how hot that is, think of a really hot day in summer as about 32 degrees Celsius or about 90 degrees Fahrenheit. That means the surface of the sun is more 100 than times hotter than the hottest day of summer! (And if you think that's hot, the core of the sun can be over 2,300 times hotter than the surface!)


Green, Paul J. "Star." World Book Online Reference Center Worldbook at NASACain, Fraser. What is a Star? 2009. Universe Today.Stars. Astronomy & time Astronomy fact files. 2002. National Maritime Museum