What To Expect From A Lunar Eclipse

On February 29th, 1504, Christopher Columbus instilled fear into the natives of Jamaica by telling them God was angry at their withholding food from his men. Knowing of a predicted total lunar eclipse that would occur that night, he told them the full Moon would rise, inflamed with wrath.

Sure enough, the Moon rose, the natives panicked and brought supplies, and once the eclipse was near its end, Columbus told them God had forgiven them. At that time, the natives didn’t know any better, but five hundred years later, we know the scientific reasons behind these celestial phenomena.

What is a Lunar Eclipse?

Eclipses top the list of many astronomers’ must-see lists. Unfortunately, while solar eclipses are breathtaking sights, sure to inspire awe and wonder in all who witness them, they are rare and fleeting, and observers must stand within the narrow path of the Moon’s shadow to be plunged into totality.

Lunar eclipses, quite beautiful in their own right, are more common, last longer, and can be seen by millions of people across the world simultaneously. But what is a lunar eclipse, and what can you expect from one?

We live in a unique time in the Earth’s history. The Moon is roughly 400 times closer to us than the Sun but is also 400 times smaller. This means the Sun and the Moon appear the same size in our sky, and, as a result, when the Moon passes between the Earth and the Sun, it can entirely cover the Sun’s disc.

That’s when a total solar eclipse occurs. Since the unlit side of the Moon is facing the Earth at this time, a total solar eclipse can only occur at the new Moon.

A total lunar eclipse is a little different and happens when the Moon passes through the shadow cast by the Earth. In that situation, the Earth is between the Sun and the Moon and the Moon appears directly opposite the Sun in the sky. In other words, a total lunar eclipse can only occur at full Moon.

Eclipses don’t happen with every new or full Moon because the Moon’s orbit is slightly tilted and, as a result, the three bodies are seldom perfectly aligned. For an observer to see a total solar eclipse, they must be standing within the Moon’s shadow cast on the Earth’s surface as the Moon passes in front of the Sun. Since the Moon’s shadow is narrow, it’s more likely to miss the Earth altogether.

A total lunar eclipse is more frequent and will last longer than a solar eclipse. This is because the Earth’s shadow is larger than the Moon, and covers a greater area of space. This being the case, the Moon is more likely to pass through it. Similarly, since the Earth’s shadow is larger, it takes the Moon longer to pass through it.

For example, totality during a solar eclipse can only last for a maximum of seven and a half minutes, whereas totality during a lunar eclipse can last for several hours.

Since a lunar eclipse happens at full Moon, it also has the advantage of being visible from any location where the Moon is visible. In theory, anyone on the night side of the Earth should be able to witness the eclipse - assuming the Moon is above the horizon, of course!


What Are the Stages of a Total Lunar Eclipse?


The Earth’s shadow has two parts to it, like a target made up of two concentric circles. The outer circle is called the penumbra and is much lighter than the innermost circle, called the umbra.

The eclipse begins as the Moon enters the penumbra. Sometimes the Moon will only pass through this outer portion of the shadow, in which case a penumbral lunar eclipse occurs.

Although quite rare, penumbral eclipses are not very spectacular. Since that part of the shadow isn’t very dark, the moonlight isn’t usually dimmed by much. In fact, you may not notice any change at all!

During a total lunar eclipse, the penumbral stage typically lasts about an hour. After that, the Moon edges into the umbra. This is when the Moon darkens and is colored by an orange glow. At this time, the eclipse is entering its partial phase, when only a portion of the lunar surface is within the Earth’s shadow. You’ll notice that the sunlit area of the lunar surface looks almost as bright as a normal full Moon, but when the Earth’s umbra hits the Moon it’ll appear coppery orange.

As with the penumbral stage, it takes the Moon about an hour to become fully immersed within the umbra. If the Sun, Earth, and Moon aren’t properly aligned, the Moon may only skim through the umbra, in which case a partial lunar eclipse occurs. When this happens, part of the Moon’s surface will appear orange while the rest almost appears at its normal brightness.


How Dark is the Moon During a Total Lunar Eclipse?

Totality begins once the Moon is fully immersed in the Earth’s shadow. At this point, the whole of the Moon appears coppery orange, but the depth of the color will vary with each eclipse. On some occasions, the Moon can be so dark that it almost disappears from view, while at other times the color may be very light or almost non-existent.

The reason the Moon changes color is because of the Earth’s atmosphere. It refracts sunlight, causing a small amount of light to strike the Moon’s surface. If there is a lot of dust in the atmosphere - for example, following a volcanic eruption - this can reduce the amount of sunlight being refracted and the Moon appears orange as a result.

Since the Moon is darker during totality, you’ll also notice more stars than during the penumbral or partial phases of the eclipse. Go outside on a moonless night and you’ll see far more stars than during a full Moon. That’s because the Moon brightens the surrounding sky, in much the same way as the Sun during the day. The fainter stars become difficult to see, leaving only the brighter stars remaining.

During a total lunar eclipse, the Moon isn’t nearly as bright as it would normally be, and many of those fainter stars become visible again. Try comparing the number of stars you see before the eclipse with the number of stars you see during totality.

Unlike the penumbral and partial phases, totality can last anywhere between a few seconds and a few hours - it all depends upon how close the Moon is to the center of the umbra. For example, if the Moon simply skims the outer edge of the umbra, totality might only last for a few minutes, but if it passes right through the center, then totality could last for nearly two hours.

Totality ends when the leading edge of the Moon reaches the penumbra again. The eclipse then slowly ends as the Moon leaves the umbra behind and passes through the penumbra, before leaving the Earth’s shadow completely. Just as before, it can take about an hour for the Moon to completely leave the umbra and then another hour for it to pass through the penumbra again.

Both solar and lunar eclipses can take hours to reach totality, but whereas a solar eclipse is over in minutes, a lunar eclipse typically gives observers the opportunity to savor the experience. There’s still a sense of awe and wonder as the Sun, Earth, and Moon align, like the inner mechanical motions of a celestial clock, and it’s easy to understand how ancient civilizations were fearful of these events. If you didn’t know better, what would you believe?

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Interested in learning more about what to expect from a lunar eclipse? Check out our Astronomy Hub!

This Article was Last Updated on 08/21/2023