How to watch solar and lunar eclipses safely

Why eclipses happen, and why not every month

A solar eclipse happens when the Moon passes between the Sun and Earth and its shadow falls on us. A lunar eclipse happens when Earth passes between the Sun and the Moon and our shadow falls on the Moon. So solar eclipses can only happen at new Moon, and lunar eclipses only at full Moon.

They don't happen every month because the Moon's orbit is tilted about 5° to Earth's. Most months the Moon passes a little above or below the Sun–Earth line. Eclipses come in 'seasons' about every six months, when the line-up is close enough.

Kinds of solar eclipse

• Total: the Moon covers the Sun completely for a few minutes along a narrow path, often only 100–250 km wide. The sky darkens, the Sun's corona appears, and the temperature drops. Many people call it the most striking sight in nature.
• Annular: the Moon is near the far point of its orbit and looks slightly smaller than the Sun, leaving a 'ring of fire'. Never safe to look at without a filter.
• Partial: seen over a much larger area on either side of the path; the Sun looks like a cookie with a bite out of it.

Protecting your eyes during a solar eclipse

Looking at the Sun, even when 99% of it is covered, can burn the retina without pain, and the damage can be permanent. Ordinary sunglasses, even several pairs stacked, are not safe.

Use eclipse glasses or handheld viewers that meet the ISO 12312-2 standard, from a reputable supplier, and check them for scratches. Never look through binoculars, a camera or a telescope unless it has a proper solar filter on the front, even while wearing eclipse glasses. A safe, cheap alternative is projection: a pinhole in card, or the gaps between leaves, cast small images of the crescent Sun on the ground.

The only time it is safe to look with the naked eye is during totality, when the Sun is completely covered. Put your glasses back on as soon as the first bright point of the Sun reappears.

Lunar eclipses: safe to watch, and red

A lunar eclipse is completely safe to look at with your eyes, binoculars or a telescope; you are only looking at the Moon. And unlike a total solar eclipse, it is visible from the whole night side of Earth at once, so most people get to see one every few years from home.

During totality the Moon usually turns copper or deep red: the 'blood Moon'. Sunlight passing through Earth's atmosphere is bent toward the Moon, and the atmosphere scatters away the blue, as at sunset. In effect, the Moon is lit by all of Earth's sunrises and sunsets at once. How red it turns depends on dust and cloud in our atmosphere.

Eclipses worth planning for

• 2 August 2027: a total solar eclipse with totality up to about 6 minutes 23 seconds, the longest on land this century, across southern Spain, North Africa (including Luxor, Egypt) and the Arabian Peninsula.
• 6 February 2027: an annular solar eclipse across South America and the Atlantic.
• 31 December 2028: a total lunar eclipse, visible from much of Asia, including Korea, as well as Europe, Africa and Australia.
• Our eclipse page shows which eclipses are visible from your city, how much of the Sun or Moon will be covered, and the local times.