The Ultimate Guide to Observing the Moon

April 23, 2021

The Moon! The Moon! Oh, how we all enjoy looking up at the Moon. The Moon is beautiful and calming, yet mysterious and foreboding. Throughout history, the Moon has inspired lore and legends. Some cultures believed the Moon possessed mythical and devious powers that could affect one’s behavior, giving rise to the word “lunatic,” which derives from the Moon’s Latin name, “Luna.” And, of course, mythical creatures like werewolves and vampires are said to prowl under the light of a full Moon.

The Moon helps to shape life and is vital to the environment here on Earth. Small nocturnal creatures take advantage of natural moonlight to scour the ground for their next meal while being vigilant for predators who may want to make a meal out of them. Wayward hikers who are lost in the woods can use moonlight to help find their way home. Sometimes, the Moon moves in front of the Sun, temporarily plunging parts of the world into eerie darkness while its shadow traverses across Earth’s surface. Mankind has been mystified by the Moon since humans first appeared on Earth and will continue to be so for as long as there is a Moon in the sky.

It’s no wonder that we are drawn to the Moon; for many of us, it has stirred our imaginations from a very young age. With countless poems, nursery rhymes, and songs written about the Moon, it plays a deep role in our lives whether we realize it or not. If you’re a newcomer to astronomy or a Moon aficionado, this guide will help you become more familiar with our closest celestial neighbor in space–your first observing target, the Moon!

Observing the Moon

The Moon is the easiest and most popular observing target to get you started on your astronomical journey. It is the only celestial object in which you can see surface detail without any optical aide. Each night, you can keep track of the Moon’s phase as it goes through its monthly lunar cycle just by using your naked eyes. Surface features such as dark gray mares and white reflective highlands are easily visible without optical aide.

Using a small 7x or 8x binocular will reveal much more surface detail, including craters, while still being easy to hand-hold with minimal shaking. A larger binocular such as a 15x or 20x model, will provide higher magnification, but will be more susceptible to shaking and should be mounted to a tripod for the steadiest views.

A telescope pointed towards the Moon will reveal incredible surface features that will come alive with detail. Because the Moon is so big and bright, you do not need the most expensive equipment to enjoy viewing the Moon–even a small, entry-level 60mm telescope at 70x will provide breathtaking views and keep you exploring for hours!

As the Moon moves in its orbit around Earth, you will notice how sunlight strikes its surface from different angles, causing it to grow or wax. Craters and mountain ranges will begin to show more dramatic detail as they become well-defined thanks to the ever-growing shadows. The best time to observe the Moon’s surface is best just a few days past first quarter phase. At this time, the Moon’s craters become more obvious from its Southern region. Details will “pop out,” especially near the terminator (the dividing line between night and day on the lunar surface).

This contradicts the old belief that the full Moon is the best time for observing the Moon. While it’s true the Moon is very picturesque during its full phase, it’s actually not the best time to observe lunar features. Why? Sunlight striking the Moon head-on washes out most of the surface with its intense glare. A full Moon can be uncomfortably bright when viewed through optics, but a Moon filter, Neutral Density filter, or Polarizing filter will reduce glare for comfortable viewing. Surface features like the Tycho crater’s impressive impact rays are easily discernable when using filters like these:

A detailed Moon map such as Celestron’s Observer’s Map of the Moon is an invaluable tool to help you quickly identify key lunar targets, so you can explore them for yourself. The locations of the most fascinating mountain ranges, seas, valleys and rilles will no longer be a mystery with a map by your side:

Top Lunar Observing Targets

	Montes Apenninus Montes Apenninus, also known as the Apennine Mountain Range, is named after the Apennine Mountains in Italy. It was formed when the Mare Imbrium basin was created nearly four billion years ago. The Apennine mountains stretch out over 370 miles and include more than 3,000 peaks. The highest peak is Mons Huygens. Measured from its base to its peak, it reaches 18,000 feet. Use a telescope at high magnification to explore this region.
	Aristarchus Aristarchus, named after Greek astronomer Aristarchus of Samos, is quite a spectacular reflectance lunar impact crater that lies in the northwest section of the Moon's near side. It’s a young formation, approximately 450 million years old and is considered the brightest of the large formations on the lunar surface. The crater is deeper than the Grand Canyon! Also, look for the largest sinuous valley or rille next to Aristarchus called Schroter's Valley. It’s shaped like a tadpole with a long tail.
	Clavius Named after Jesuit priest Christopher Clavius, Clavius is the second largest crater formations on the Moon and is among the oldest. Located in the southern highlands to the south and near the crater Tycho, Clavius is over 143 miles in diameter and is best seen in binoculars and small telescopes during the Moon’s first and third quarter phases. The Stratospheric Observatory for Infrared Astronomy (SOFIA) detected water molecules specific to H2O in the floor of Clavius crater.
	Copernicus Named after astronomer Nicolaus Copernicus, Copernicus is one of the Moon’s most famous impact craters with a prominent bright ray system which extends out to 500 miles. Copernicus measures 58 miles wide with a large depth of 12,467 feet. Its outer rim gives it a noticeable hexagon shape. Just off center inside its crater, a lunar mountain rises 3,940 feet above the crater’s floor. Use binoculars to spot the crater, but a telescope will provide you with an “astronaut’s” view.
	Lunar X and V The infamous Lunar X and Lunar V are a pair of small, eerie optical illusions on the Moon, visible only when sunlight falls at the right time on the lunar topography. Lunar X, also known as the Purbach Crater or Werner Cross, appears around First Quarter near the terminator between the craters La Caille, Purbach, and Blanchinus. Lunar X is only visible when sunrise is occurring over this region—just four short hours! Occurring at the same time as Lunar X, Lunar V is located higher north in the Mare Vaporum region and forms the letter “V.” It’s slightly bigger than Lunar X and sits on the terminator line. Challenge yourself to spot both letters at the same time!
	Mare Crisium Mare Crisium, or the English name of Sea of Crisis, is a large 345-mile-wide asteroid impact basin located northeast of Mare Tranquillitatis (Sea of Tranquility). Mare Crisium is the only major mare that is not connected to any other large mare system on the front facing side of the Moon. It’s visible in binoculars but better seen in a telescope.
	Petavius Petavius, also known as the “Clock Crater,” is an unusual double-walled impact crater located near the Moon’s southeastern limb and is best seen for a few days following new Moon. It has long and straight rille called Rimae Petavius, which represents the clock’s long minute hand. A smaller fissure represents the short hour hand. What time is it? It’s time to use your telescope to see for yourself!
	Plato Named after ancient Greek philosopher Plato, this large lava-filled impact crater is approximately 68 miles in diameter, seen prominently near the upper northern section of the Moon. Plato has one of the darkest and smoothest crater floors. Polish astronomer Johannes Hevelius called it the “Greater Black Lake.” Use a small telescope at about 100x magnification to observe a triangular section of the western rim that appears to have broken off when an asteroid impacted the crater.
	Rupes Recta (Straight Wall) The Straight Wall, more formally known as Rupes Recta, or Latin for straight cliff, is a large-scale linear surface fault more than 62 miles long, between 1.2 and 1.9 miles wide, and ranges from 787 feet to 984 feet in height. It’s an easy target for small telescopes appearing as a small black line (shadow) across the floor of Mare Nubium approximately a day or two after first quarter. When sunlight strikes the Straight Wall from the opposite side near Third Quarter, the cliff appears white. The Straight Wall is a highly popular target for amateur astronomers. Don’t miss this one!
	Schiller Schiller is an unusual-looking elongated crater shaped like an oval shoeprint. It is located at the southwestern edge of the Moon, an area known to be highly engrossed with impact craters. Schiller is about 112 miles long and has a well-defined crater rim. It’s a fine target for telescopes due to its shape and proximity to the Moon’s southern edge.
	Sinus Iridum Latin for Bay of Rainbows, Sinus Iridum is an asteroid impact crater shaped like the letter “C,” which merges into vast lava plain called Mare Imbrium. Sinus Iridum is located on the Moon’s northwestern edge and spans nearly 250 miles. Its semicircular rim consists of a mountain range called Montes Jura.
	Tycho Named after the Danish astronomer Tycho Brahe, Tycho is a younger crater which formed about 108 million years ago and is one of the most prominent craters on the Moon. It’s very noticeable as a bright “button,” or the “Lady on the Moon’s pendant.” Located on the Moon’s southern highlands, Tycho’s most striking features are the bright rays of ejected material that streak out over 1,600 miles—appearing like a dazzling pendant. Inside the crater is a triangular shaped central mountain rising nearly a mile high. Tycho and its rays are best seen during full Moon with your binoculars or telescope.

Moon Facts

The Moon was formed shortly after the Earth, about 4.5 billion years ago. There are several theories of how the Moon was formed. Some scientists believe it was captured by the Earth’s gravity while passing nearby. However, most present-day scientists theorize that early on in the Solar System’s existence, a wandering Mars-sized planet crashed into Earth. This fiery collision hypothesis known as Theia Impact or “Big Splash,” may have resulted in huge amounts of vaporized debris ejected into space that eventually condensed to form the Moon. Imagine having ringside seats to witness that cosmic collision!
Like most objects in the Solar System, the Moon orbits around Earth in an elliptical pattern. At its closest approach (perigee), it comes within 225,623 miles. At its farthest approach (apogee), it is 252,088 miles away from Earth. On average, the distance from Earth to the Moon is approximately 238,855 miles away.
The Moon’s diameter is 2,159 miles, about the same distance from Los Angeles to Grand Rapids, Michigan.
The Moon is our closest neighbor in the Solar System. Although it may appear to be the same size as the Sun as seen from Earth, this is a sheer coincidence. The Sun’s diameter is about 400 times larger than that of the Moon, but it is also about 400 times farther away!
The Moon is Earth’s only natural satellite and is the fifth largest moon in the Solar System. It’s even larger than the dwarf planet, Pluto.
There is hardly any erosion visible on the Moon’s surface features because there is no wind and no weather. Footprints from astronauts who once walked on the Moon in the 1960s and 1970s are still there today and will not be going anywhere unless there is a meteor strike or future astronauts or spacecraft trample them.
The Moon’s atmosphere is called the exosphere. Although it does not contain any oxygen for humans to breathe, scientists have discovered a very thin layer of gases including sodium and potassium not found in the atmospheres of Venus, Earth, or Mars.
October 26, 2020, NASA announced that its Stratospheric Observatory for Infrared Astronomy (SOFIA) had detected water on the sunlit surface of the moon. Previously, it was thought the Moon’s surface was completely devoid of water except perhaps in its dark polar crater regions where sunlight never penetrates.
Temperatures on the moon are extreme, ranging from boiling hot to freezing cold, depending on which side of the Moon is in sunlight or darkness. Highs can hit 260 degrees Fahrenheit, while lows can dip to a frigid minus 280 degrees Fahrenheit.
Earth’s tides—the rise and fall of ocean levels worldwide—occur as a result of the Moon’s and Sun’s gravitational attraction. The Moon’s pull causes the ocean to bulge towards it and is matched by a slightly smaller bulge on the opposite side of Earth. This results in a high tide. When the Sun, Moon, and Earth are all aligned, a Spring Tide occurs, the highest high tide and lowest low tide possible. Spring Tides occur during a new and full Moon. Neap Tides occur when the Sun, Earth, and Moon form a 90-degree angle to each other, during a first quarter and third quarter Moon. The bulges from the ocean cancel each other out, and both high tide and low tide are much weaker. Next time you observe the Moon’s phase, you’ll have an idea of what’s taking place in the ocean.
There is no such thing as the “Dark Side of the Moon,” regardless of the popular Pink Floyd song. The front and back sides of the Moon receive equal amount of sunlight. However, from Earth, we can only view one side of the Moon due, once again, to an odd coincidence. The Moon takes precisely 27.3 days to complete one revolution around the Earth and precisely 27.3 days to complete one rotation on its axis. This is called tidal locking. At times, a small part of the “dark side” (approximately 5%) is visible due to a wobble or lunar libration as the Moon orbits. In all, we can see about 59% of the lunar surface.
Although it takes 27.3 days for the Moon to complete a revolution, it takes 29.5 days to change from new Moon to new Moon as the Earth is also moving along in its orbit around the Sun.
In 1959, the Soviet spacecraft, Luna 3, transmitted the first grainy images of the Moon’s far side and humans had their first glimpse of this hidden lunar surface. In 1968, Apollo 8 astronauts became the first humans to see the far side firsthand when they orbited the Moon.
The United States completed six crewed Apollo missions to the Moon’s surface and landed 12 astronauts in all from 1969 to 1972: Apollo 11, 12, 14, 15, 16, and 17. Apollo 13 was scheduled to land on the Moon but suffered a major explosion that damaged the Service Module. All three Apollo 13 astronauts orbited the Moon and returned to Earth safely.
Popular myth tells us that the Moon is made of cheese. This is, in fact, a cheesy fable.

Special Lunar Phenomena to Explore

Most observers starting out in amateur astronomy seek out the Moon as their first observing target. It’s big, bright, and easy to find on almost any night. But did you know that there are many lunar phenomena that occur—regularly or on occasion—that you can observe right from your own backyard?

	Earthshine Earthshine occurs when sunlight is reflected off the Earth's surface, onto the Moon, and then back to Earth again. The dim light of Earthshine can faintly illuminate the “night” side of the Moon’s surface, revealing some of its surface markings. Earthshine is best observed a few days before and after a new Moon, during its waxing or waning crescent stages after sunset or before sunrise in deep twilight. A binocular or telescope is recommended.
	Lunar Halo A lunar halo is caused by the refraction of moonlight by ice crystals in thin, high altitude cirrus clouds. This phenomenon can appear in any season and makes a 22-degree circle around a deep gibbous or full Moon. The halo is usually white in color but may sometimes show faint colors of the rainbow. According to folklore, a ring around the Moon was said to be a sign that rain was on the way. While this could be true because cirrus clouds generally precede storm systems, it is not guaranteed. Use your unaided eyes to observe this cool celestial delight!
	Lunar Occultation A lunar occultation takes place when the Moon passes in front of a distant object such as a planet or star. The Moon occults dim stars regularly, but these occultations are not observable due to Moon’s overwhelming brightness. But occasionally, the Moon passes in front of a bright star such as Spica or Aldebaran and planets such as Mars or Jupiter. These events are best seen through a telescope and are fun to watch. The star or planet seems to disappear behind the Moon, only to reappear a short time later.
	Lunar Conjunction A lunar conjunction occurs when the Moon comes within close range of a bright star or planet. It usually takes place in the evening or morning sky. The most common conjunctions occur during the Moon’s waxing or waning crescent phases. A famous lunar conjunction occurred back in 2008 when the Moon, Jupiter and Venus came together to form a smiley or sad face depending on your location.
	Solar Eclipses A solar eclipse can only take place when the Moon is new and comes between the Sun and Earth to cast its shadow (umbra) on the Earth. However, a solar eclipse does not take place each new Moon because the Moon’s orbit is tilted relative to Earth’s orbit. Therefore, the Moon’s shadow often passes above or below Earth. There are three types of solar eclipses: total, annular (ring of fire), and partial. Remember, the only time it is safe to observe a solar eclipse with your unaided eyes is during totality. Under no circumstances should you ever observe an annular or partial eclipse without safe solar glasses or through a proper solar filter for your optics. The next annular eclipse visible in the US will take place on October 14, 2023. The next total solar eclipse visible in the US will take place six months later, on April 8, 2024. The two paths will cross through the state of Texas.
	Lunar Eclipses A lunar eclipse can only take place during a Full Moon when the Earth is between the Sun and Moon, and the Moon moves into the Earth’s shadow. Anyone located on the night side of Earth will be able to witness the eclipse, and it will be completely safe to do so. No eye protection is required. There are three types of lunar eclipses: total, partial, and penumbral. Unlike a total solar eclipse where totality only lasts a few minutes, the length of totality during a total lunar eclipse can last longer than 90 minutes. The Earth also casts a lighter shadow called the penumbra. If it touches the Moon, any darkening will most likely be seen if the Moon is closer to the umbra shadow zone. In most penumbral eclipses, the shadow is quite subtle, so that most people will hardly notice that a lunar eclipse is occurring. The next total lunar eclipse visible in the US will take place on May 26, 2021 and favors mainland western US, Alaska, and Hawaii.
	Moon Illusion When we watch the Moon rise, it often appears much larger when it is close to the horizon than when it is high overhead. This celestial phenomenon is known as the “Moon illusion.” Watching a huge yellow-orange Moon rising above buildings, treetops, or distant mountains is something to behold. But why does this optical illusion occur? One theory is that the Moon looks bigger because there are smaller land objects around to compare it with. When the Moon is higher up in the sky, there isn’t anything other than stars or planets to compare it with. In modern times, psychologists concluded that the Moon illusion is just a trick of the imagination. There are a few ways you can see for yourself that the Moon is the same size no matter where it is in the sky. Next time you see the Moon rise, take several photos of it, and later take photos of the Moon after several hours have passed. You can see for yourself that the Moon is the same size in both images. You can also use a paperclip to bend and shape to the Moon’s outline and compare it again several hours later. These simple experiments are easy to do, and you’ll see for yourself that some things are not always what they seem.

Faces on the Moon

When looking up at the full Moon, you may notice many light and dark areas. The lighter areas are referred to as highlands while darker areas are volcanic in nature, called maria, which is Latin for seas. We may think we can see various patterns, such as the famous “Man on the Moon,” or the “Lady on the Moon,” because our brains are trained to recognize face shapes in our surroundings. The next time you’re out moongazing, have fun with this! If you let your imagination run wild, you may begin to see other unique shapes form such as a rabbit, jack-o’-lantern, and more!

Phases of the Moon

As the Moon orbits around Earth, sunlight hits different parts, causing it to appear to change shape. The Moon goes through a cycle of phases from new Moon to full Moon and back to new Moon again. This cycle takes about 29.5 days, and the entire cycle can be broken down into eight phases. They are:

	New Moon: When the Moon is between the Earth and Sun and is not visible
	Waxing Crescent: Seen after dusk as a thin crescent of light and begins to move away from the Sun.
	First Quarter: The Moon continues to grow and appears half lit.
	Waxing Gibbous: The Moon becomes bigger and brighter and appears somewhere between a first quarter and full Moon.
	Full Moon: When the Sun and Moon are aligned on opposite sides of Earth, and the Moon’s face is fully illuminated.
	Waning Gibbous: The Moon begins to shrink after a full Moon and appears somewhere between a full and third quarter Moon.
	Third Quarter: The Moon continues to shrink and appears half lit.
	Waning Crescent: Seen prior to dawn as a thin crescent of light as it moves closer to the Sun.

Monthly Moon Names

Every 29.5 days, we are rewarded with a beautiful, bright, full Moon. We often refer to the different full Moons throughout the year by their own unique names. Some of these names date back hundreds of years when Native Americans used the Moon to help keep track of time and the seasonal changes in weather. As of 1955, the most popular Moon names were officially added to The Farmer’s Almanac. For example, the Harvest Moon, which takes place closest to the Autumnal Equinox, is famous for the extra moonlight it provides on fall evenings. The extra light aided farmers as they harvested their summertime crops. The 12 full Moons of the Rupes year include:

January’s Moon: Wolf Moon, Moon After Yule, Old Moon, Ice Moon, Snow Moon
February’s Moon: Snow Moon, Hunger Moon, Storm Moon, Chaste Moon
March’s Moon: Worm Moon, Crow Moon, Sap Moon, Lenten Moon
April’s Moon: Pink Moon, Seed Moon, Sprouting Grass Moon, Egg Moon, Fish Moon
May’s Moon: Flower Moon, Milk Moon, Corn Planting Moon
June’s Moon: Strawberry Moon, Mead Moon, Rose Moon, Honey Moon
July’s Moon: Buck Moon, Hay Moon, Thunder Moon
August’s Moon: Sturgeon Moon, Corn Moon, Red Moon, Green Corn Moon, Grain Moon
September’s Moon: Harvest Moon, Full Corn Moon
October’s Moon: Hunter’s Moon, Blood Moon, Sanguine Moon
November’s Moon: Beaver Moon, Frosty Moon
December’s Moon: Cold Moon, Oak Moon, Long Nights Moon

Other Moon Names

In addition to the traditional 12 Moon names of the year, there are other unique names for different Moon events:

New Moon	A New Moon occurs when the Sun and Moon are on the same side of the Earth, and we cannot see the front facing side because it is not lit up by the Sun. On that day, the Sun and Moon rise and set near the same time, although the Moon will usually pass above or below the Sun. A New Moon is opposite of a full Moon in its monthly orbit.
Black Moon	A Black Moon refers to an additional New Moon that appears in a month, in a season, or an absence of a full Moon in the month. Due to February having the fewest days, about once every 19 years, February does not have a full Moon. This phenomenon also creates two Blue Moons: one in January and one in March. The dark skies of the Black Moon make it the perfect time to observe deep space objects.
Blue Moon	A Blue Moon does not actually turn a shade of blue; it is the second full Moon that appears in one calendar month. Since a full Moon occurs every 29.5 days and most months are 30 days long, it’s possible to get two full Moons in a month but only “once in a Blue Moon!” There is also a seasonal Blue Moon, which occurs when there are four Full Moons in an astronomical season. A Seasonal Blue Moon will occur on August 22, 2021.
Red/Blood Moon	Although the Moon never turns blue, it can take on another hue. A Red or Blood Moon is another name for a total lunar eclipse. When the Moon passes completely through the Earth's dark shadow, the umbra, the Moon appears rusty red, hence the name. The next total lunar eclipse visible from the US will occur on May 26, 2021.
Supermoon	A Supermoon is a full Moon that coincides with perigee (the closest the Moon comes to the Earth in its elliptic orbit). The Supermoon is slightly larger than an average full Moon as observed from Earth. The technical name is a perigee syzygy or a full Moon at perigee. A full Moon at perigee appears roughly 14% larger in diameter than at apogee (when it is smallest). The term “Supermoon” was coined in 1979 by American astrologer Richard Nolle. Supermoons in 2021 will take place on April 27, May 26, and June 24.

Helpful Observing Hints

Tip #1: Use an Astronomy App or Moon Chart	Using a detailed Moon map is a great way of learning where to locate these celestial wonders or any other celestial objects anytime of the year. It may be an old fashion learning tool, but it just works. (See link under Observing the Moon.) The most modern and informative tools today can be found in astronomy apps such as Celestron’s SkyPortal mobile app. This full featured planetarium app is included with the purchase of any Celestron telescope, available from the Apple App Store or Google Play. SkyPortal instantly provides new telescope owners with a wealth of information at their fingertips, including audio and written descriptions about various objects. It also provides its celestial coordinates, a real-time sky map, rise and set times, physical and orbital parameters.
Tip #2: Seeing Conditions	Steady seeing conditions are critical while observing objects such as planets, the Moon, or double stars, although deep sky objects such as nebulae and galaxies are less affected by poor seeing conditions. Avoid nights of bad seeing when our atmosphere is turbulent, and your lunar targets appear like shimmering blobs in your telescope’s eyepiece. Start with low magnification and work your way up if the views remain steady. During a night of good seeing, you will be amazed how sharp and detailed lunar features can appear.
Tip #3: Telescope Cooldown	Cool your telescope down! Make sure you bring your telescope outside about an hour or so before you plan to observe to cool it to ambient temperature. It is important for the telescope to reach thermal equilibrium with the outside air temperature to avoid distorted views. Telescopes with large mirrors and lenses may take longer to properly cool down for the best views.
Tip #4: Collimation	Collimate, collimate, collimate! If you own a Newtonian or Schmidt-Cassegrain telescope, make sure your telescope’s optics are collimated. It can make a difference when it comes to discerning fine lunar detail. If the optics are slightly out of alignment, you may be cheating yourself out of seeing the clearest and sharpest images.

Final Thoughts

We are quite fortunate to have such a beautiful Moon, like an old friend who will always be there to inspire us. It’s hard to imagine life as we know it without the Moon shining down upon us. Today, we know more about the Moon than ever before. Countless missions were sent to study the Moon since the 1950s, and twelve Apollo astronauts successfully walked on the Moon’s surface and brought home hundreds of pounds of lunar rocks and soil for analysis. But there is always more to be learned in humankind’s quest for knowledge.

The Moon, with its desolate landscapes, is just waiting to be explored again by a new generation of backyard astronomers and future astronaut explorers. Next time you observe the Moon, you may want to think of what Galileo must have felt when he first looked at the Moon through his modest telescope. There’s no doubt he would be amazed at the lunar views seen through your telescope and that would give you something to smile about.

To browse Celestron telescopes, binoculars, and accessories that will make your lunar viewing experience more enjoyable, please click here.

Clear skies and happy Moon viewing!

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