Never look at the Sun

Why

The Sun is so bright that the light focused by your eye's lens can burn the back of the eye, and the back of the eye has no pain nerves, so you don't feel it. Sunglasses cut glare but let through far too much light to make looking at the Sun safe.

Binoculars and telescopes collect even more light. Never point them at the Sun, and never leave them where a child might.

Eclipses

During an eclipse of the Sun, the Moon covers some or all of it. It is tempting to look, and people do get hurt. NASA's guidance is to use eclipse glasses or a handheld solar viewer that meets the ISO 12312-2 international standard, and to check them for scratches. Only during the brief total part of a total eclipse can glasses come off, and only where totality happens.

A safe way with no glasses at all: a pinhole projector. Poke a small hole in a card, stand with your back to the Sun, and let the light through the hole fall on a second card. The little image is the Sun, and during an eclipse you see the bite taken out of it.

Eclipses of the Moon are different

An eclipse of the Moon is safe to watch with bare eyes: it is just the Moon, dimmed and often reddish, in Earth's shadow. Only the Sun needs protection.

Safe ways to enjoy the Sun

The Sun can be watched without looking at it. Watch shadows: put a stick in the ground and mark the end of its shadow every hour, and you have made a sundial. In winter the shadows are longer at noon than in summer, because the Sun is lower.

Watch sunrise and sunset colours, but look at the clouds and the sky around the Sun rather than at the Sun itself. And notice where it sets from a window each month: it moves along the horizon, farthest south around the December solstice and farthest north in June.

If your child wants to see the Sun's face, NASA's own pictures from its space telescopes show sunspots and flares safely, on a screen.