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Why only part of the Sun is covered
Every solar eclipse begins as a partial one. Around the central path of a total or annular eclipse, the Moon's lighter outer shadow, the penumbra, covers a region thousands of kilometres wide. Standing in it, you see the Moon pass in front of only part of the Sun.
Some eclipses are partial everywhere: the Moon's shadow passes above or below Earth, so no one sees totality or a ring. And because every solar eclipse looks partial across the wide region around its central track, a partial view is what most people get.
What the percentage means
Observatories give a magnitude or a percentage for your location. A bite of 30 percent hardly changes the daylight. At around 80 percent the light starts to look odd and cooler, and above 90 percent you may notice real dimming.
Your own spot matters a lot: the same eclipse can be nearly total on one side of a country and small on the other. Look for local timings and the coverage for your own city.
How to watch safely
- Glasses with ISO 12312-2. Check for the marking; sunglasses, smoked glass and photographic film do not protect you.
- Keep them on. Even when 90 percent of the Sun is covered, the rest is intense enough to injure.
- Project it. A pinhole in card or the gaps in a colander cast small crescents on the ground, with no risk.
- Protect optics. Binoculars, telescopes and camera viewfinders need a proper solar filter on the front.
Why a partial eclipse is still worth it
It lacks the sudden twilight of totality, but the crescent Sun is a striking sight, especially through filters, and it is an easy way to introduce children to astronomy with an adult in charge. If you can travel, a total solar eclipse is a different experience.
The full rules are on the safety page, and the eclipses hub compares all six types.
In folklore
A bitten Sun appears in myths from many places, often as a beast taking a mouthful before giving it back. Astrologers read partial eclipses as gentler turning points. Both are traditions, and neither needs worry.
Questions people ask
Can I look at a partial eclipse without glasses?
No. The uncovered part of the Sun is still bright enough to damage your eyes, so protection is needed throughout the eclipse.
Why do I see a different amount than my friend abroad?
The Moon's shadow falls differently on every place. Coverage is greatest near the central line and smaller the farther away you are.
Do animals react?
Some do. Birds may fall quiet and insects may begin their evening sounds, especially when coverage is high.