Introduction: The Sun is the brightest natural object in our sky. It is a star. It gives off light. We see many stars in the nighttime sky and only the Sun in the daytime sky. Actually, all of the stars are still in the sky during the day. We just can't see them because the Sun is so bright that it outshines the other stars! But, if the Sun is a star like the stars we see at night, then why is it so much brighter?

The reason the Sun looks so bright is because of its distance from Earth. Earth is about 150 million kilometers (93 million miles) from the Sun. This is a large distance. However, in astronomical distances, it isn't far. The Sun is the only star in our solar system. The next closest star is much farther away and in a different solar system. Stars farther from Earth may actually be as bright as the Sun (or even brighter!), but because they are so far away, they appear to be less bright than the Sun. Given two identical stars, the one closer to us will look brighter than the one farther away even though they both give off the same amount of light.

Distance also explains why the Sun looks so large in the sky compared to other stars. Since the Sun is the closest star to Earth, it appears larger compared to more distant stars. However, the Sun is really an average star. Many of the distant pinpoints of light we see in the sky at night are actually stars larger and brighter than the Sun! They are just much, much farther away from us.

Be careful! Never look directly at the Sun - even with sunglasses! Have you ever had a sunburn? The rays from the Sun that cause sunburns can also damage your eyes.

Directions for This Lesson: In this lesson, you will learn why the Sun looks so bright. First, try the practice questions. Then, watch the video lesson to learn more.