1. When you see the moon, think of the whereabouts of the sun. After all, it’s the sun that’s illuminating and creating the dayside of the moon. Moon phases depend on where the moon is with respect to the sun in space. For example, do you see which moon phase is being shown in the illustration above? The answer is, it’s a full moon. The moon, Earth and sun are aligned with Earth in the middle. The moon’s fully illuminated half – its dayside – faces Earth’s night side. That’s always the case on the night of a full moon. Don’t just take my word for it. Go outside. No matter what phase of the moon you see in your sky, think about where the sun is. It’ll help you begin to understand why the moon you see is in that particular phase. 2. The moon rises in the east and sets in the west, each and every day. It has to. The rising and setting of all celestial objects is due to Earth’s continuous daily spin beneath the sky. Just know that – when you see a thin crescent moon in the west after sunset – it’s not a rising moon. Instead, it’s a setting moon. At the same time, though … 3. The moon takes about a month (one moonth) to orbit the Earth. Although the moon rises in the east and sets in the west each day (due to Earth’s spin), it’s also moving on the sky’s dome each day due to its own motion in orbit around Earth. This is a slower, less noticeable motion of the moon. It’s a motion in front of the fixed stars. If you just glance at the moon one evening – and see it again a few hours later – you’ll notice it has moved westward. That westward motion is caused by Earth’s spin. The moon’s own orbital motion can be seen in the course of a single night, too. But you have to watch the moon closely, with respect to stars that are near it, over several hours. The moon’s eastward, orbital motion is easiest to notice from one day (or night) to the next. It’s as though the moon is moving on the inside of a circle of 360 degrees. The moon’s orbit carries it around Earth’s sky once a month, because the moon takes about a month to orbit Earth. So that the moon moves – with respect to the fixed stars – by about 12-13 degrees each day. 4. The moon’s orbital motion is toward the east. Each day, as the moon moves another 12-13 degrees toward the east on the sky’s dome, Earth has to rotate a little longer to bring you around to where the moon is in space.
Thus the moon rises, on average, about 50 minutes later each day. The later and later rising times of the moon cause our little buddy, the moon, to appear in a different part of the sky at each nightfall for the two weeks between new and full moon. Then, in two weeks after full moon, you’ll find the moon rising later and later at night. Simple? Maybe...keep observing the moon each night and you will begin to see the pattern.
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Mrs. TaylorI love science! Everything about the world is interesting and never boring. I love to study plants, animals, insects, and people. My favorite subjects are my students who are the most unique organisms on the planet! Categories |