Solar and lunar eclipses
An eclipse happens when the Sun, Moon and Earth align.
During a solar eclipse, the Moon passes between the Sun and Earth. As a result, the Moon completely or partially covers the Sun.
During a lunar eclipse, also called a blood moon, Earth passes between the Sun and the Moon. The resulting shadow on the Moon turns it orange to dark red. Lunar eclipses only happen around a full moon.
Whether the Moon casts a shadow on Earth, or the other way around, we can divide this shadow into two regions. The region of full shadow is called the ‘umbra’. No light from the Sun directly enters this region, although some is redirected there by Earth’s atmosphere in the case of a lunar eclipse. Total solar and lunar eclipses are visible from within the umbra.
The region of partial shadow is called the ‘penumbra’. When you are in a region on Earth within the Moon’s penumbra, you will see a partial solar eclipse. When the Moon moves through Earth’s penumbra it will dim slightly, but this is often difficult to detect with the naked eye. A partial lunar eclipse occurs when the Moon partially enters Earth’s umbra (with the remainder within the penumbra).
The white dashed lines indicate how rays of sunlight travel from the Sun to Earth. Because these rays travel in straight lines, tracing these rays from the Sun’s edges also traces out the umbra and penumbra.
The 2026–2028 ‘European solar eclipses’
Remember: never look directly at the Sun, even when partially eclipsed, without proper eye protection such as special solar eclipse glasses, or you risk permanent eye damage.
[Image description: This infographic explains how solar and lunar eclipses work. On the left, a diagram labelled 'Solar eclipse' shows the formation Sun-Moon-Earth, with the Moon tracing a shadow on Earth as it blocks the Sun's light. On the right, a diagram labelled 'Lunar eclipse' shows the formation Sun-Earth-Moon, with the Earth casting a shadow over the Moon as it blocks the Sun's light. The three astronomical bodies are labelled, as are the umbra and penumbra shadow regions. Dashed lines mark out the path of sunlight.]
