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Shapes of the Moon's surface

The surface of the Moon seen from the Earth seems uneven. There are dark and light areas on it. The
human imagination has suggested that the dark areas could be seas like on the Earth and the light ones continents. The very bright areas, on the other hand, have always been seen as mountains as they actually are. The periodic changes in the light face of the Moon have always given people mysterious and romantic inspiration. The picture is taken with the help of a telescope (by IH, Finland).


Aim: Get acquainted with the shapes of the Moon’s surface and get to know the names of the various areas and major objects.

Explorations: The Moon is our nearest celestial body. Its average distance from the Earth is about 384 000 kilometres. The Moon is an easy object to observe. Dark and light areas as well as some objects clearly brighter than the surroundings can be distinguished even with the naked eye. People have tried to give an explanation to these areas and it has been easy to find similarities with the terrestrial regions they know. Dark regions have been imagined to be seas, light regions plains and bright areas mountains. In fact there are no liquid regions on the Moon. Dark areas are large craters with liquid stone material from the inner parts. They were born in a collision event. These areas reflect sunlight differently from the higher plains.

There really are mountains on the Moon and they look like bright areas. Craters are the most special objects on the Moon’s surface. They can be seen by using binoculars or a telescope. The craters were born when meteorites hit the surface of the Moon. The surface shaped by these collisions has kept its shape well since the surface is coherent and solid with no moving continental plates. Hard surface has crushed into small stones and sand dust due to continuous bombing of meteorites.

Take a closer look at various regions on the Moon’s surface. Before that, recall with the students the phases of the Moon and the rotation time that enables the special phenomenon: the Moon always shows her face to the Earth.

1)  Observe the Moon with the students outdoors at first with the naked eye. Discuss observations. Ask students to describe their findings and later on to also draw them. Explain the visibility and substance of the regions with various colour shades.


2)  Observe the half Moon or the crescent Moon by using binoculars and a telescope. The full Moon is too bright for the eyes if observation devices are used. That is the case in the darkness of the night and especially if filters are not used. Discuss new findings, i.e. the craters and the mountains. Ask students to explore especially the region of the terminator, i.e. the border between dark and light. There it is possible to see beautiful lace-like edges of the craters.


3) * Explore the moon maps with the students. Divide students into three or four groups. Give each group a task to find a few most familiar objects from the maps. Objects may have themes like seas, mountains, plains and craters. The results will be presented to the whole class and discussed together.

The most well-known seas are named as follows: Mare Tranquillitatis is the Sea of Calmness, Mare Crisium is the Sea of Dangers, Mare Ibrium is the Sea of Rains, Mare Serenitatis is the Sea of Brightness and Oceanus Procellarum is the Ocean of Storms.

The most well-known mountains are Montes Alpes, the Alps, Montes Apennines, the Apennines; Montes Altai, the Altai Mountains; and Montes Caucasus, the Caucasus Mountains.

Less known are the names of the plains, many of which mean bays because of a misinterpretation. These are: e.g. Sinus Aestuum, the Bay of Heat; Sinus Iridum, the Bay of Rainbows; and Sinus Medii, the Centre Bay. Vallis Alpina,  the Valley of Alps, also belongs to this group.

The fourth group is the craters. They have gotten their names mostly from scientists. Some craters have been named according to the most famous Finnish scientists, e.g. F.W.A. Argelander, Yrjö Väisälä and A.I. Virtanen.


4) * Explore together with the students a moon map. Try to find more interesting objects. Teams can compete with each other on the amount of objects found. The students can use literature and the Internet as source material in search of further information on their findings and present them in the class literally or by using pictures.


5) * An interesting and even challenging task for the students is to sketch a moon map. The teacher provides the class with a moon map which already includes the longitudes and latitudes as well as the names of the most famous objects. The map is enlarged to a size of at least A3 and then cut into eight pieces of different sizes mainly according to eight
orientations. To increase the complexity of the task, enlarge some pieces a little. It makes the fitting together more difficult. This task can also be given to the teams, and they can compete with each other for speed. Finally, each group can present the oddest objects of the topic they have chosen.


6) * Try to determine the depth of a crater that can be clearly seen due to a shadow created by the sunlight. The height and shadow of a mountain that is known can be of help in this.

Methods: Observation in nature is most important. Interpretation of the moon maps, expression of the impressions, getting to know the names, and drawing of the findings.

Materials: Binoculars, a telescope if available, moon maps, filters, craft materials.

Pondering: Also discuss with the students the back side of the Moon, not seen from the Earth. What does it look like there? Find information on the Internet. Find the area on which the spacecraft landed.



Evaluation of results: Compare and discuss the moon maps made by the teams. Also compare the Moon’s face during
various phases. Discuss the changes in the Moon’s orbit: sometimes nearer and sometimes farther from the Earth. How could that be seen in the observations?


Hints: During the full Moon it may be worthwhile to use darkened glasses when observing the Moon by binoculars or a telescope. A picture of the Moon can also be reflected on the wall or cardboard.


Keywords: Moon, Moon’s surface, crater, terminator, formation of the surface, Moon’s seas.


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