lunar eclipse

A lunar eclipse is a phenomenon in which the Earth prevents the light of the Sun from reaching the Moon, creating a cone of shadow that obscures the Moon. The totally eclipsed Moon acquires a characteristic reddish color due to the dispersion of the refracted light by the Earth's atmosphere.

Unlike solar eclipses, which can be seen only from a relatively small part of the Earth and last only a few minutes, a lunar eclipse can be seen from any part of the Earth where it is nighttime and last for several hours.

Types of eclipses

Due to the angular size of the Sun, the shadow cast by the Earth consists of two zones: the umbra and the penumbra. In the umbra there is no direct solar radiation, while in the penumbra solar radiation is only partially blocked. Eclipses are therefore classified into total, partial and penumbral eclipses. An observer will say that he or she has seen a total eclipse when the Moon is completely located in the umbral zone. When only part of the Moon is in the umbra, the eclipse is partial. If the Moon is located in the penumbra, the eclipse will be penumbral, and only a subtle darkening of the lunar surface will occur.

¿When do eclipses occur?

The plane through which the Moon orbits the Earth (shown in blue in the figure below) is tilted 5º with respect to the plane through which the Earth (and Moon) orbits the Sun (shown in yellow). Because eclipses require the near-perfect alignment of the three celestial bodies, eclipses occur very few times during the year. The Moon takes about one month to complete one revolution around the Earth, so if the two planes coincided we would have 12 eclipses of the Sun and 12 eclipses of the Moon each year. In practice, the number of eclipses that occur each year is between 4 and 7, including those of the Sun and Moon. In many cases the eclipses are partial (or even penumbral only for lunar eclipses), and visible from a fraction of the Earth's surface. When the Moon is close to the Sun in the sky, in the new Moon phase, there is a possibility of a solar eclipse. When the Moon is in the opposite direction of the Sun, visible all night in full Moon phase, there is a possibility of a lunar eclipse.

Upcoming Lunar eclipses

Upcoming solar eclipses visible from Spain

• Total lunar eclipse, March14, 2025
• Total lunar eclipse, September 7, 2025
• Partial lunar eclipse, August 28, 2026
• Penumbral Lunar eclipse, February 20, 2027