Reference
Explanations of the terms these pages and the interactive model use, written for readers who have not met them before.
Glossary
Every term this site uses, in alphabetical order. Each has its own page, with a diagram and the traps that make it easy to confuse with its neighbour.
Articles
- When is the next solar eclipse?
The next total, annular and partial solar eclipses, and why the question almost always means "from where I am" — which has a very different answer. - How to watch a solar eclipse without hurting your eyes
A certified filter for every moment except totality itself, and nothing else will do. Sunglasses, smoked glass, exposed film and phone screens are not filters, and the danger is silent. - Is it worth travelling to see totality?
A 99% partial eclipse and a total one are not the same event at different strengths. The difference is not a matter of degree, and it arrives in the last few seconds. - How often do solar eclipses happen?
Two to five a year worldwide, which sounds frequent until you ask about one place — where totality comes round about once every 375 years. Both numbers follow from the same geometry. - How to read an eclipse path map
The line is where totality lasts longest, the band around it is where totality happens at all, and the wide outer region is where you see a partial eclipse. Three different claims, drawn together. - How an eclipse is predicted
Two analytic series for the positions of the Sun and Moon, a geometric test for whether the shadow reaches the ground, and a root-find for the moments the discs touch. - Why two sources give different eclipse times
Compare any two eclipse predictions far enough ahead and they disagree by seconds, and by kilometres on the ground. Almost none of that is error — it is how fast the Earth will be turning on the day. - Photographing a solar eclipse
A filter on the lens for every phase but totality, one exposure plan written down in advance, and a decision made early about whether to photograph the first one you see at all.