Question

Why is it safe to watch an eclipse of the Moon but not an eclipse of the Sun

Answer 1

During a solar eclipse, the Sun's intense rays can damage your eyes, making it unsafe to watch. In contrast, during a lunar eclipse, the Moon is reflecting sunlight, making it safe to observe.

An eclipse of the Sun is not safe to watch because the Sun's intense rays can damage your eyes.

Even during a partial eclipse, when the Moon is covering part of the Sun, the uncovered part is still dangerous to look at.

However, an eclipse of the Moon is safe to watch because the Moon is not emitting its own light, but rather reflecting sunlight.

When the Moon is fully covered by Earth's shadow during a lunar eclipse, it is safe to observe.

Answer 2

A solar eclipse occurs when the moon crosses in front of the Sun, blocking some or all of its rays. A lunar eclipse happens when the moon is directly behind the earth, blocking the moon from receiving light. The only light comes from the light on earth's reflected shadow.

You can look at a lunar eclipse because there is very little light or none at all. You can't look at a solar eclipse because you are looking directly at the sun unless it is complete. Before totality, only some of the Sun is blocked, causing your pupils dilate to let in more light. Since they do this, more of the Sun's rays can be let in to the eye, which effectively allows your eyes to burn.

Some doctors and eye care specialists say that after someone complains of blindness after looking at a solar eclipse unaided, they can see what the Sun and moon looked like at the time that they looked at it, as it is burned onto their retinas.