|That orbed' maiden
With white fire laden
Whom mortals call the Moon.
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moon·struck /ˈmunˌstrʌk/ Pronunciation Key - Show Spelled Pronunciation[moon-struhk] Pronunciation Key - Show IPA Pronunciation
The surface of the Moon has two hemispheres with rather asymmetric properties; the near side of the Moon is substantially different from the far side.
The near side is divided into light areas called the lunar Highlands and darker areas called Maria. The Maria (literally, "seas"; the singular is Mare) are lower in altitude than the Highlands. The dark material filling the Maria is actually dark, solidified lava from earlier periods of lunar volcanism. Both the Maria and the Highlands exhibit large craters that are the result of meteor impacts. However, there are many more such impact craters in the Highlands.
The far side of the Moon (unseen from the Earth) has a very different appearance than the near side. In particular, there are almost no Maria on the far side, but plenty of impact craters.
Different parts of the surface of the Moon exhibit different densities of cratering, which implies different ages: the maria are younger than the highlands, because they have fewer craters.
The bulk density of the Moon is 3.4 g/cc, which is comparable to that of (volcanic) basaltic lavas on the Earth. Hhowever, the bulk density of the Earth is a much higher 5.5 g/cc because of the dense iron/nickel core.
The Moon is coverered with a gently rolling layer of powdery soil with scattered rocks that is called the regolith; it is made from debris blasted out of the lunar craters by the meteor impacts that created them.
One striking difference between the lunar surface material and that of Earth concerns the most common kinds of rocks. On Earth, the most common rocks are sedimentary, because of atmospheric and water erosion of the surface. On the Moon, there is no atmosphere to speak of and little or no water, and the most common kind of rock is igneous ("fire-formed rocks"). Geologically, the lunar surface material has the following characteristics: The Maria are mostly composed of dark basalts, which form from rapid cooling of molten rock from massive lava flows. The Highlands rocks are largely Anorthosite, which is a kind of igneous rock that forms when lava cools more slowly than in the case of basalts. This implies that the rocks of the Maria and Highlands cooled at different rates from the molten state and so were formed under different conditions.
The monthly progression from new moon to full and then to new moon is the most easily and widely recognized of the motions in the heavens. How can we explain the phenomenon of lunar phases?
Where is the moon in relation to the sun when the moon is full?
Where is the moon in relation to the sun when the moon is new?
Where is the moon in relation to the sun when the moon is in either first or third quarter phase?
Also, some more subtle questions to discuss are:
What is the shape of the line dividing light from dark (the terminator) on the lunar surface?
Suppose the moon is in the 1st quarter phase. In what phase would the Earth appear to an astronaut on the Moon? What about a full moon?
In what direction does the moon appear to move during the night?
In what direction does the moon appear to move from night to night?
If the new moon occurs when the moon lies between us and the sun while the full moon occurs when we are between the moon and the sun, why do solar and lunar eclipses not happen every month?
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