The evening Moon of the summer months seems to draw more attention than any other time of the year. With lots of people outdoors in the nine o’clock hour when twilight starts to grip the landscape, everyone seems to look up at the Moon.
You can see so much of the Moon and you just don’t realize it. So let’s take some time to look at the surface of the Moon with the naked eye and binoculars—a telescope might really blow your mind!
That’s what happened to me and many other amateur astronomers who pointed their first telescope at our next door neighbor in outer space. The Moon is where my passion for stargazing began, looking at all those craters and mountains named after the very famous people and places of Earth.
You might not experience the lunacy I have about stargazing, but even spending a few casual minutes looking up at our Moon can change your perspective about things in outer space.
As the crescent Moon begins to be seen like a fingernail hanging in the western twilight, it’s morning on an alien world that has a “day” that lasts 29 Earth days. That’s why amateur astronomers count the Moon days from New phase, with a seven-day-old Moon being First Quarter, the 14-day Moon is full phase, 21 day Moon is Last Quarter and the 28-29 day Moon is New phase. So, a 5-day Moon is a big crescent a couple of days before First Quarter.
Some facts about what causes the phases: Our natural satellite is one-fourth the size of Earth at 2,160 miles, its airless and mostly light rock without many heavy iron-like elements. Observed from above Earth’s North Pole, the Moon revolves counter-clockwise (eastward in our skies) at a speed of 2,100 mph. Since the Earth spins eastward at 1,100 mph, the Moon travels ahead of the Earth’s rotation and moves 12.5 degrees left (eastward) each day. The Moon makes one complete orbit about the Earth in 29 days, keeping one side gravitationally locked toward our sphere, 7,920 miles in diameter.
The “older” the Moon gets as it moves eastward, the more we see and the brighter the globe until reaching its brightest at full phase. This brightening moonlight washes out faint stars night by night until just the brightest ones are visible around the full phase. That’s why amateur astronomers love a moonless night, because we can see “deep sky” objects like nebula and star clusters that can’t be seen through moonshine.
Look at the Moon with just our eyes; we obviously see dark splotches against bright areas. Ancient stargazers thought the dark areas were seas of water, and called them the Latin name Maria. The bright areas were assumed to be land with mountains.
As the Moon progresses in its early days of crescent phase, the first Maria visible is Mare Crisium, the Sea of Crisis, a distinct oval in the upper right edge. To its left is the rather large Mare Serenity (Sea of Serenity) below it Mare Tranquility (Sea of Tranquility), both having irregular shores.
Once the Moon is at full phase, the giant Maria called “Ocean of Storms” (Oceanus Procellarum) is visible. The north border is curved with mountain ranges and called Mare Imbrium, Sea of Rains, which may be the impact region of a giant asteroid. There are other smaller Maria around the globe facing Earth. Some of these are Mare Frigoris, Mare Humorium, Mare Nectaris, Mare Nubium and Mare Vaporum.
Curiously, the back side of the Moon is lacking in the dark Maria seen on the earth-facing side. One theory is when the Moon became locked in the Earth’s gravity; the molten lava was drawn to that side, oozing to the surface.
Looking at the Moon in any kind of binoculars will reveal craters in those lunar seas, as well as mountain ranges. Two craters are hinted at with just our eyes: at full phase long streaks of bright rays can be seen coming from the crater Tyco in the south, and between Oceanus Procellarium and Mare Imbrium can be seen a bright spot that is crater Copernicus.
Once you start navigating around the Moon with the aid of optical instruments, the details of craters and mountains are so numerous that remembering the names of them all is a challenge. But having a lunar atlas handy will give you literally hours of exploring the names of craters and even places where the six Apollo moon landings occurred.
Because the Moon is so close and bright, it doesn’t take a very large telescope to see detail as small as 10 miles wide. A 3-5 inch lens refractor telescope or 6-8 inch mirror reflector telescope is enough light gathering power to see many lunar details.
Every visible feature on the Moon has a name, and the early Moon cartographers chose to honor some of the brilliant scientists, authors and leaders of mother Earth. There are the prominent craters Aristotle, Plato and Archimedes, as well as Copernicus, Kepler and Newton.
As the terminator moves across the lunar surface, each night presents the Moon in detail that is different than the night before. It’s along this division between day and night that most detail is seen as the shadows are long. The same is true during early morning and late evening when sunlight casts long shadows and the earthly landscape is more interesting than midday. When we look at the Full Moon in a telescope, it looks bland and features are hard to distinguish because there are now shadows.
Fascination with the Moon is a hobby that can evolve into drawing the lunar features or photographing them. In learning your way around the Moon, you take the first step in exploring the Universe right from your backyard.