The Ultimate Guide to Observing Lunar Eclipses

You may have noticed that the full Moon sometimes undergoes a startling transformation. Slowly, a curved shadow appears, taking a “bite” from the Moon’s disk. The shadow retreats or completely engulfs the Moon until it takes on an eerie red hue. The appearance of a red Moon frightened many ancient observers. They believed the gods were angry and had taken the regular Moon away as punishment. Surely, they thought, it was a bad omen and a harbinger of hardship and misery.

Today, scientists comprehend the orbital mechanics of our Solar System. They understand eclipses and can predict them well in advance. Rather than stoking fear, lunar eclipses delight modern-day observers.

Total lunar eclipses are not as exciting as total solar eclipses, which turn day into “night” and back again. But unlike solar eclipses, lunar eclipses do not require special protective filters or other specialized gear. Because they are not limited to a narrow path of totality, many more observers can enjoy total lunar eclipses for much longer.

On November 7-8, 2022, the second of two total lunar eclipses of the year will occur. The Moon will traverse through the Earth’s umbral or darker shadow, exciting those watching in person or on the Internet. How bright or dark will the Moon be? What color will the Moon appear? You will have to see the eclipse to find out. Start planning your evening now to have a great view of one of nature’s grandest nighttime spectacles. If you are curious to learn more about lunar eclipses and the details of November’s total lunar eclipse, read on!

What is a lunar eclipse?

The Moon does not give off light of its own. On Earth, we can only see the Moon because it reflects sunlight.

The Earth casts a shadow out into space. Every so often, its shadow falls upon the Moon. A lunar eclipse can occur only during a full Moon when the Sun, Earth, and Moon are aligned. The Moon moves into the Earth’s shadow—first, a lighter shadow called the penumbra, and then a darker shadow called the umbra. Lunar eclipses last several hours from start to finish. Under favorable conditions, the Moon can remain in the umbra in a total eclipse for almost two hours.  

Why doesn't a lunar eclipse occur each month?

The Moon orbits around the Earth and reaches full Moon to full Moon approximately every 29.5 days. Therefore, it seems logical that a lunar (or solar) eclipse would occur every month during each full (or new) Moon.

However, the Moon’s orbit around Earth is not in a flat plane. It is tilted about 5 degrees compared to the plane of Earth’s orbit around the Sun, called the ecliptic. Because the Moon usually passes above or below the Earth’s shadow, a lunar eclipse does not occur at every full Moon.

Types of Lunar Eclipses

	Total Lunar Eclipse A total lunar eclipse only happens when the full Moon moves into the Earth’s circular (umbral) shadow. In most cases, the Moon will not completely disappear. Instead, it takes on an eerie glow best described as reddish. The exact shade can vary with orange, brown, and yellow tones. But where does a “Blood Moon” get its color? Sunlight passing through Earth’s atmosphere scatters and bends (refracts) into the shadow’s cone. All the sunrises and sunsets on Earth are refocused on the Moon, giving it a ruddy glow during totality.
	Partial Lunar Eclipse A partial lunar eclipse occurs when the Sun, the Earth, and the full Moon are in line but not precisely enough for a total eclipse. Only a part of the Moon’s surface moves into the Earth’s umbral shadow, while the uneclipsed section of the Moon remains illuminated by direct sunlight. If the Moon moves deep into the umbra but not all the way, it can take on a slight red-orange tint, but not across the entire lunar disc.
	Penumbral Lunar Eclipse A penumbral lunar eclipse occurs when the Sun, the Earth, and the full Moon are in line but even less precisely. Earth blocks some of the Sun’s light while the Moon remains inside the faint outer part of Earth’s shadow, the penumbra. A penumbral lunar eclipse is not very impressive because the Earth’s outer shadow is much lighter than its inner darker shadow. You may detect subtle darkening if the Moon moves close to the umbral shadow. A penumbral lunar eclipse can be partial or full depending on how much of the Moon enters this fainter shadow. A penumbral lunar eclipse is often difficult to distinguish from a typical Full Moon.

Stages of a Total Lunar Eclipse

A lunar eclipse is one of the easiest celestial events to observe. If you have time and are in an ideal location, why not try to watch a partial or total lunar eclipse from start to finish, including when the Moon enters and exits the penumbra? Here are the seven stages of a total lunar eclipse to watch for:

• Penumbral eclipse begins (first contact): The Moon enters the Earth’s lighter shadow. The lunar eclipse begins.
• Partial eclipse begins (second contact): Earth’s umbra begins to cover the Moon, making the eclipse more noticeable.
• Total eclipse begins (third contact): The Moon moves entirely inside the Earth’s umbra. Depending on atmospheric conditions, the Moon can take on different colors, such as red, orange, yellow, or brown.
• Maximum eclipse (peak stage): The Moon moves as far into the umbra as possible.
• Total eclipse ends (fourth contact): Earth’s umbra moves away from the Moon’s outer limb. The Moon slowly begins to light up.
• Partial eclipse ends (fifth contact): Earth’s umbra completely leaves the Moon’s surface.
• Penumbral eclipse ends (sixth contact): The Moon leaves the Earth’s lighter shadow. The lunar eclipse ends.

The Danjon Scale

In 1921, French astronomer André-Louis Danjon came up with the five-point Danjon Scale to measure the appearance and brightness of the Moon during a total lunar eclipse. The scale contains five “L values” from 0 to 4.

• L = 0  Very dark eclipse. The Moon is almost invisible, especially during mid-totality.
• L = 1 Dark eclipse, gray or brownish in coloration. Details are distinguishable only with difficulty.
• L = 2 Deep red or rust-colored eclipse. We see a very dark central shadow while the outer edge of the umbra remains relatively bright.
• L = 3 Brick-red eclipse. The umbral shadow usually has a bright or yellow rim.
• L = 4 Very bright copper-red or orange eclipse. The umbral shadow has a bluish, very bright rim
(Source: NASA eclipse website.)

Tips for Watching a Lunar Eclipse

• Research the time and date for the entire lunar eclipse for your area and follow along as the eclipse progresses.
• You won’t need special equipment or safety glasses. Go outside and enjoy the view with your own eyes, binoculars, or a telescope!
• If you have binoculars or a telescope available, they will enhance the views and reveal details on the Moon’s surface when basking in Earth’s shadow. Use low and high-power magnification to monitor the eclipse.
• During the partial phase, look for the curved shape of the Earth’s shadow as it moves over the Moon.
• During totality, try to notice what color and how bright or dark the Moon appears and compare it with the next total lunar eclipse. There can be a wide range of variations in color or brightness. Use the Danjon scale above for reference.
• Although you can enjoy watching a total lunar eclipse from the city, you may want to travel to a dark-sky site for a different viewing experience. Imagine seeing the Moon in a total eclipse surrounded by a sea of stars.
• Before the lunar eclipse begins, the full Moon will be very bright and wash out all but the brightest stars near it. Look for fainter stars that suddenly appear near the Moon during totality.
• If you like to draw, sketch the eclipse in progress and note when prominent lunar craters enter and leave the umbra. Use a Moon map for reference.
• Use an adapter to attach your smartphone or DSLR camera to your telescope to take excellent, detailed images. For some telescope types, adding a focal reducer will help frame the entire eclipsed Moon rather than a magnified, cut-off image.
• If an eclipse occurs during warmer times of the year, make sure you have bug repellent handy. If an eclipse occurs during colder times of the year, bundle up and dress warmly, especially if you are observing with children. Don’t forget the coffee and hot chocolate!

Lunar Eclipse Facts

• The eclipsed Moon can remain inside the umbra for more than 100 minutes, but the maximum duration of totality for a solar eclipse is only 7.5 minutes.
• Some lunar eclipses can last up to 3 hours and 45 minutes from start to finish.
• Lunar and solar eclipses usually occur in pairs—two weeks apart about every six months. The next pair will appear this Fall—a partial solar eclipse on October 25, 2022, and a total lunar eclipse on November 7-8, 2022.
• Unlike solar eclipses, lunar eclipses are safe to observe with your naked eyes, binoculars, or telescopes. There is no danger in watching a lunar eclipse during its partial or total phases because you are looking at the Moon entering the Earth’s shadow and not direct sunlight.
• The Moon often appears reddish due to an effect known as Rayleigh scattering. Sunlight is refracted and scattered by the Earth’s atmosphere, and longer, red wavelengths are bent and directed toward the shadow cone and onto the Moon.
• If you were an astronaut on the Moon during a total lunar eclipse, you would see the black disk of the Earth blocking out the Sun. You’d also see a brilliant red ring of sunlight scattered through the Earth’s atmosphere. This red ring consists of all of Earth’s sunrises and sunsets, seen simultaneously.
• When the Sun, the Earth, and the Moon align, it is called a “syzygy.”
• When we can observe both the Sun and the eclipsed Moon simultaneously, it is called a Selenelion or Selenehelion. This phenomenon can occur just before sunset or just after sunrise. Both the eclipsed Moon and Sun appear above the horizon on opposite sides of the sky. It seems impossible with Earth positioned between them, but it can happen due to the refraction of light through the Earth’s atmosphere, which causes both objects to appear higher in the sky than their actual positions.
• According to NASA, two to four solar eclipses can occur yearly, but lunar eclipses are less frequent. The maximum number of eclipses in any given year is four solar and three lunar.
• There could be one, two, three, or no lunar eclipses in any given year.
• More people on Earth can view a lunar eclipse than a solar eclipse.
• The Greek philosopher Aristotle is often credited with proving that Earth was round due to its curved shadow on the Moon during a lunar eclipse.
• The color and brightness of a total lunar eclipse depend on the amount of dust and volcanic ash in the Earth’s atmosphere. The total lunar eclipse of December 1992 was very dark due to the tremendous amount of dust and ash in the atmosphere after Mount Pinatubo’s eruption in the Philippines.

The Next Total Lunar Eclipse

Get ready! We are a few weeks away from the next total lunar eclipse visible to those in parts of the Western and Eastern Hemispheres. On the night of November 7-8, 2022, observers in North, Central, and Northwestern South America, the Pacific Ocean, Australia, and Asia will observe a total eclipse of the Moon. During this eclipse, the Moon will remain inside the umbra for nearly an hour and a half: 85.7 minutes!

(Image courtesy of NASA.)

For much of the Western Hemisphere, this total lunar eclipse will occur during the early morning hours, so you should plan accordingly. Be prepared for interrupted sleep or even an “all-nighter,” especially if you report to work in the morning; in addition Daylight Savings Ends on November 6th. Take an early nap, dress warmly, grab a chair, and enjoy the spectacle!  

If you miss November’s total lunar eclipse, you must wait until March 13-14, 2025, for the next one. This eclipse will favor the Western Hemisphere—mainly the Americas. There will be penumbral and partial lunar eclipses in 2023 and 2024, so we will update this lunar eclipse guide with more information before they occur.

Observing Tools

Click to browse Celestron telescopes, binoculars, and accessories for the lunar eclipse.

The Beaver Moon of November will amaze us with a spectacular show. So, sit back, relax, and share one of Mother Nature’s most majestic events with your family and friends. Watch in awe as the Earth’s shadow creeps upon the Moon and slowly begins taking “bites” — deeper and deeper until the dark umbra takes on new colorful shades as if someone has dimmed the moonlight. Think of what the ancient astronomers must have felt as you gaze upon the eclipsed Moon—only to breathe a sigh of relief, knowing that the Moon will return to normal after passing through Earth’s shadow in its journey around the Earth.   

 Clear skies and happy lunar eclipse viewing!

Other articles you might be interested in: Ultimate Guide to Observing the Universe