THE MOON •The Moon was probably made 4.5 billion years ago when a large object hit the Earth and blasted out rocks that came together to orbit round the Earth. They eventually melted together, cooled down and became the Moon. For another 500 million years pieces of rock kept striking against the surface of the Moon. • You can see the surface of the Moon by using a pair of binoculars or a small telescope. The Moon’s surface shows the damage caused by these large pieces of rock hitting it billions of years ago. The surface is covered in craters, pits and scars. • From the Earth we can only see one side of the Moon; the other side is always turned away from us. Photographs from space show a similar scarred surface on the other side. • The Earth has a much greater surface than the Moon and was also hit by debris (the rocks from explosions and collisions) but over time the damage has disappeared. The wind and rain in the Earth’s atmosphere has helped to erode the pits and craters. • The Moon has no atmosphere and so we can still see the damage caused billions of years ago. • If you look at the Moon when it is nearly full you can see the dark areas which are known as the seas. (They are all given Latin names, such as Mare Serenitatis – the Sea of Serenity, or Mare Frigoris – the Sea of Cold).These are not really seas but are huge expanses of smooth dark lava. Figure 1. A map of the Moon. • All parts of the Moon are lit in turn by the Sun. As it rotates round the Earth we see different fractions of the sunlit half, or hemisphere, of the Moon. These are known as the phases of the Moon, or lunar phases. The Moon changes from a thin crescent to a full moon and back again to a crescent in one month (actually 29 days, which is a lunar month). Figure 2. The Phases of the Moon. • This diagram shows the phases of the moon, from a new moon, which you can hardly see at all, round to a full moon and back again in just over four weeks. Follow the phases in an anticlockwise direction(the opposite way from how the hands of a clock move). • The waxing Moon. “Waxing” means growing. After the new moon appears in the sky as a tiny sliver of light the moon waxes. It grows into a crescent, curving to your left as you look at it and then into a half moon. This takes a week and so the period is described as the Moon’s first quarter. • The waxing gibbous Moon. Gibbous means humped and describes the shape of the Moon as it grows from a half moon to a full moon. Another week has passed and this is the Moon’s second quarter. • The waning Moon. “Waning” means shrinking. Now the Moon begins to get smaller again – it “wanes”. The third quarter takes us from a full moon to a half moon again, but this time it is the right hand side of the moon that shines. • The waning crescent Moon. The last quarter takes us from a half moon back to a crescent moon, facing right, and to a point where the moon disappears. • When the Moon is a crescent and only the crescent is being illuminated by the Sun, you can often see the shadow of the rest of the Moon. This is caused by reflection of sunlight from the Earth. It is sometimes called “the old moon in the new moon’s arms”. Figure 3. The effect of earth shine on the moon. • The gravity of the Moon, the pull which it exerts on the Earth, causes two high tides on the Earth every day – one every 12 hours and 25 minutes. • The first man to make proper maps of the moon was Galileo. Galileo did not invent the telescope but by 1609 he had developed a telescope that could magnify objects to 20 times, and with this telescope he began his careful study of the Moon’s surface. • The first person to walk on the Moon was the American astronaut, Neil Armstrong, who stepped out of his space landing craft, the Eagle, on 21 July 1969 with these famous words, “That’s one small step for man, one giant leap for mankind”. Figure 4. A photograph of the Earth taken from the surface of the Moon. • The Moon is 239,000 miles, or 384,000 kilometres away from the Earth. • The Moon is much smaller than the Earth, with a diameter of 2159 miles, or 3476 kilometres. It is airless, waterless and lifeless.
Posted on: Thu, 13 Mar 2014 11:34:15 +0000
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