It’s almost time for the year’s big celestial event: a total eclipse of the Sun. Tomorrow afternoon, the Moon will pass directly between Earth and the Sun. That will block the Sun’s disk. The sky will grow dark, with a pink glow around the horizon. Stars and planets will pop into view. And the Sun’s faint outer atmosphere, the corona, will look like silvery ribbons around the Moon.

Totality will be visible along a narrow path. In the United States, it’ll stretch from Eagle Pass, Texas, to Houlton, Maine. Several major cities are along that path; the largest is Dallas. At most, totality will last for a bit less than four and a half minutes.

Skywatchers in the rest of the contiguous U.S. will see a partial eclipse — the Moon will cover only part of the Sun’s disk.

For those lucky enough to find themselves inside the path of totality, it’s perfectly safe to look at the Sun when it’s fully eclipsed. At all other times, though, the Sun is much too bright to look at directly. Even a 99-percent-eclipsed Sun is bright enough to cause eye damage. To see it safely, use proper eclipse glasses, or a piece of welder’s glass — number 14 or darker.

If you’re close to a leafy tree, you can follow the eclipse by looking at the ground — the shadows project tiny images of the eclipsed Sun. You can also look at the shadow of a colander or similar device. So enjoy this beautiful alignment — but do it safely!

More tomorrow.

Script by Damond Benningfield