Sea of Rains, Lunar Mountains, and Craters
| Polish version is here |
Our Moon, the only natural satellite of Earth, has always exerted a profound influence on virtually all living organisms. From a physical and biological perspective, its mass plays a crucial stabilizing role on Earth’s axis of rotation—without this effect, sudden and unimaginably drastic climate changes would likely have prevented life from developing at all. Thanks to the Moon’s gravitational influence—visibly evident in tidal phenomena observable with the naked eye—Earth’s rotational speed has slowed to its current rate. Finally, the lunar cycle serves as a biological rhythm regulator for many organisms—for example, the coral species Acropora palmata always spawns at dusk three to four days after the full moon.
For humans, the Moon—being the nearest celestial body and possessing surface features visible to the naked eye—has influenced our culture and imagination for centuries. This is evident in traditional calendars used by followers of many religions or the division of the Gregorian calendar into months and weeks. The lunar cycle also plays a role in religious holidays: in the Roman Catholic Church, Easter always occurs on the first Sunday after the first full moon of spring. In popular imagination, the crescent Moon is often associated with lovers, while the full Moon has become linked with less pleasant phenomena, such as werewolves and vampires.
Observing our natural satellite is relatively simple and highly rewarding. No specialized equipment is required for basic observations—a good pair of binoculars, a small telescope, or a camera with adequate zoom is perfectly sufficient.
Observation
April 2019, around 11:00 PM – Zaborze (Poland)
suburban conditions, moderate light pollution
The photograph below was taken as a so-called one shot, meaning it was captured without additional imaging techniques, particularly without stacking. As a result, it closely resembles what anyone can observe through binoculars. The image shows the northern part of the lunar disk, with directions (N, S, E, W) labeled from the observer’s perspective. A wider-field photograph with labels and descriptions can be found here.
The Sea of Rains (A, Mare Imbrium) is the second-largest lunar mare and can easily be seen with the naked eye. To the east lies the smaller Sea of Serenity (B, Mare Serenitatis), distinguished by its nearly circular shape—this “sea” has a diameter of about 700 km. South of these two areas is the Sea of Vapors (C, Mare Vaporum), while the Sea of Tranquility (D, Mare Tranquillitatis) is partially outside the frame. To the north stretches the Sea of Cold (E, Mare Frigoris). Similar to maria but usually smaller in size are lunar bays and lakes. Examples include the Bay of Heat (F, Sinus Aestuum), as well as the Lake of Dreams (a, Lacus Somniorum) and the Lake of Death (b, Lacus Mortis).
Lunar hills and mountains are another fascinating feature of the Moon’s landscape. The photograph clearly shows the mountain ranges surrounding Mare Imbrium. From south to north, these include Carpathian Mountains (α, Montes Carpatus), Apennine Mountains (β, Montes Apenninus), Caucasus Mountains (γ, Montes Caucasus), Alps (δ, Montes Alpes), and Jura Mountains (ε, Montes Jura). In the Alps lies Mons Blanc (δ1), with a height of approximately 3.6 km. Slightly to the north is Alpine Valley (δ2, Vallis Alpes), which is about 10 km wide at its central section.
Impact craters are also prominent features. One of the most impressive formations of this type is Copernicus (1), located in the eastern part of Ocean of Storms (Oceanus Procellarum, mostly outside the frame). The crater’s floor is about 46 km in diameter, with a rim width of approximately 22 km. The outer rim stands just over 1 km high, while the inner walls rise more than three times as high. The outer slopes are gently inclined. Other labeled craters include Gay-Lussac (2), Eratosthenes (3), Archimedes (4), Autolycus (5), Aristillus (6), Timocharis (7), Lambert (8), Pytheas (9), Plato (10), Aristoteles (11), and Eudoxus (12).
Here, I have described only a small portion of the many fascinating features that can be observed using commonly available equipment. After all, the photograph shows only a small section of the Moon’s disk. I encourage everyone to look up at our natural satellite on a clear night. As a final tip: the easiest time to observe details of the Moon’s surface is during the crescent phase, near the terminator line. Why? I think you’ll discover the answer yourself.
Photo 1 Parameters:
- Total exposure time: 1/320 second
- Canon EOS 60D
- ISO: 500
- Lens: zoom type (used at fmax = 250mm)
- A filter was used to reduce the effects of artificial light pollution and atmospheric glow
- Mount: photographic tripod
Marek Ples