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What is a Lunar Eclipse?

J. Beam
J. Beam

A lunar eclipse is a celestial event that occurs when the Earth blocks all or part of the sun’s rays, preventing them from reaching the moon and thus creating a shadow across the moon. A lunar eclipse can happen between two and four times per year. There are three types of lunar eclipses, two of which are visible to anyone on the nighttime side of the Earth when the eclipse occurs.

The moon orbits the Earth every 29.5 days. The circling of the moon around the Earth causes the phases of the moon. The phases of the moon are: New, New Crescent, First Quarter, Waxing Gibbous, Full, Waning Gibbous, Last Quarter, and Old Crescent. With the exception of the New Moon, the various phases of the moon are visible and easily identified. For a lunar eclipse to occur, the moon must be in the Full phase and pass through some portion of the Earth’s shadow.

Lunar eclipses occur between two and four times per year.
Lunar eclipses occur between two and four times per year.

Depending on the location and alignment of the sun, the Earth, and the moon, one of three types of eclipses can occur. A Penumbral Lunar Eclipse occurs when the moon passes through Earth’s penumbral shadow. This lunar eclipse is only visible with the aid of high-powered, astronomical viewing devices. Most standard telescopes are not optically strong enough to allow a viewer to see a penumbral eclipse and so they are of very little interest to people outside of the field of astronomy.

A Partial Lunar Eclipse occurs when a portion of the moon passes through the Earth’s umbra and a portion of the moon is shadowed from the sun. A partial lunar eclipse is visible, even to the naked eye. The final type of lunar eclipse is the Full Lunar Eclipse and occurs when the entire moon passes through the Earth’s umbra, creating a complete shadow across the moon. A full eclipse, witnessed under the ideal circumstances, such as clear skies, late at night or very early in the morning, can be the most spectacular lunar eclipse to see.

Contrary to a solar eclipse, which requires protective eye gear to witness safely, a lunar eclipse requires no special viewing instrumentation. Most meteorologists are well aware of a lunar eclipse in advance and typically broadcast the date and approximate ideal viewing times. Depending on the refraction of the sun’s rays from the Earth’s atmosphere, a lunar eclipse will cause the moon to cast off a dark brownish, blood red, or burnt orange hue. The best places to view a partial or total lunar eclipse are those located farthest away from large cities with lights.

Frequently Asked Questions

What is a lunar eclipse and how does it occur?

A lunar eclipse happens when the Earth comes between the Sun and the Moon, casting a shadow on the Moon. This can only occur during a full moon when the Sun, Earth, and Moon are precisely aligned or very close to alignment. The Earth's shadow has two parts: the penumbra (partial shadow) and the umbra (full shadow), which create different types of eclipses.

Are lunar eclipses common occurrences?

Lunar eclipses are relatively common, with at least two happening each year, but not all are visible worldwide. According to NASA, there can be up to five lunar eclipses in a year, although it's rare. The visibility of an eclipse depends on the night side of the Earth at the time of the eclipse.

What are the different types of lunar eclipses?

There are three types of lunar eclipses: total, partial, and penumbral. A total lunar eclipse occurs when the Moon passes entirely into the Earth's umbra. In a partial lunar eclipse, only a portion of the Moon enters the umbra. During a penumbral eclipse, the Moon moves through the Earth's penumbral shadow, causing a subtle shading but no dramatic change in appearance.

How long does a lunar eclipse last?

The duration of a lunar eclipse can vary. A total lunar eclipse can last up to 1 hour and 40 minutes in the Earth's umbra, with the whole event taking up to 3 hours and 40 minutes from start to finish, including the penumbral stages. Partial and penumbral eclipses are generally shorter in duration.

Can a lunar eclipse affect animals or the environment?

While there's no concrete evidence that lunar eclipses have a significant impact on animals or the environment, anecdotal reports suggest some animals may become disoriented or change their behavior during an eclipse. However, these effects are temporary and do not have long-term consequences for wildlife or ecosystems.

Is it safe to watch a lunar eclipse with the naked eye?

Yes, it is perfectly safe to watch a lunar eclipse with the naked eye. Unlike solar eclipses, which require protective eyewear to prevent eye damage, lunar eclipses are harmless to observe. This is because the light reflected from the Moon, even during an eclipse, is not intense enough to cause harm.

Discussion Comments


@Logicfest -- Let's not forget that solar eclipses are pretty darned rare. I can't remember the last time we had a solar eclipse. Meanwhile, we have several lunar eclipses every year.

While it is hard to deny that solar eclipses are more dramatic than lunar eclipses, it is well worth mentioning that the rarity of solar eclipses have something to do with their popularity, too.

Oh, and couple that with the way solar eclipses have been used to predict omens, show off God's power in the Bible, etc. and there is a lot more mystique built up around them.

A lunar eclipse? Those are just very common and not as dramatic as a solar eclipse.


The problem with the lunar eclipse is that few people even see the blasted thing, much less realize that it is going on at all. If we can't see the moon, we either assume that's just another moon phase to deal with or that the moon is hiding behind the clouds again.

People get all excited about solar eclipses. They tend to ignore lunar eclipses. And, there you have it.

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    • Lunar eclipses occur between two and four times per year.
      By: marcel
      Lunar eclipses occur between two and four times per year.