Back to  How does the sun glow? Is the sun a star?

Your questions were fairly similar so we combined them and gave them to Gord, "The Professor", to see what he had to say.

When you look up at the night sky, you see thousands of little points of light that we call "stars". In the daytime, when it is not cloudy, you can see one very bright object in the sky that we call the Sun. The Sun is really just another star, except that it is much, much closer to us than all the other stars. In fact, if you were to put the Sun as far away as even the nearest star, it would look so dim that you would hardly be able to see it! Of all the stars that we can see in the sky our sun is one of the smallest. Stars that are the same size or smaller than our sun are just too dim to be seen, unless you use a telescope. Even though our Sun is bigger than you can imagine, the stars that we can actually see are gigantic in comparison -- they are very large indeed!

All stars, including our sun, are giant balls of hydrogen gas in which thousands of nuclear explosions are happening every second! There is so much gas that gravity is very strong in the centre. The gravity is so strong that it forces the hydrogen gas to make explosions like in the H-bomb (the "H" stands for hydrogen!) Obviously, these explosions produce a lot of heat and this is what makes the Sun glow so brightly. The temperature in the centre of the Sun might be as much as 20 million degrees Celsius! By comparison, the outer edge of the Sun is at a "cool" 6 thousand degrees Celsius!

When you look up at the night sky and look very carefully at the stars, you will notice that they actually have different colours. Some are icy blue, some are yellow, while some are sort of orange-ish. These colours are clues to how hot the stars are and how old they are. The blue ones are very hot (around 20 thousand degrees Celsius on the outside) and very young (maybe only a few million years old!) The yellow stars (our Sun is a yellow star) are at about 6 thousand degrees Celsius and are "middle aged" (about 5 billion years old). The orange stars are at about only 3 thousand degrees Celsius and are very old (about 10 billion years old). Next time you are outside at night, try to see the different colours of stars!

Here is a National Geographic Magazine that has a special feature about our Sun. Look on page 494.

How does the sun glow? Is the sun a star?

Drew, Cassandra, room 11, Mrs. Pottery

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