![]() This process is called ‘waxing’ and takes about a fortnight. If you are in the Northern Hemisphere, the Moon’s right side grows with light from a crescent to a semicircle and then a gibbous (more than a semicircle but less than a full circle) shape until finally it becomes a glorious full moon. This means there is no dark side of the Moon, just a side facing away from the Earth.įrom Earth though, it looks like the Moon goes through different lit-up phases. And just as we have half the planet lit and the other in darkness at any one time, the Sun is always shining on half the Moon. Like the planets, we only see the Moon because it reflects the Sun’s light. To grasp why the Moon’s appearance changes, we need to bring in the Sun. As it rises at a later time, the Moon appears in a different part of the sky. This shift means Earth has to rotate a little longer to bring the Moon into view, which is why moonrise is about 50 minutes later each day. It causes the Moon to move 12–13 degrees east every day. This movement is from the Moon’s orbit, which takes 27 days, 7 hours and 43 minutes to go full circle. By looking at where the Moon is in relation to stars in the background one night, and then comparing to where it is several hours later or on the next night you’ll notice it has moved east. The lunar orbit is slower and harder to see – but you can still spot it. ![]() Just like the Sun and the night time stars, the Moon’s apparent rising in the east and setting in the west each day is not from the Moon’s orbit around the Earth, it’s from the Earth spinning. If we first think about the Moon in relation to the Earth, we can explain how it appears to travel across the sky over the course of a night, and why it rises and falls at different times and in different locations. Most vividly, its entire appearance changes over the course of two weeks, morphing from a bright circle to a circle sliced in half and finally fading to nothing.Īll these changes seem complicated but each one can be explained by thinking about where the Earth, Sun and Moon are in relation to one another. And from night to night it rises and falls at different times and in different parts of the sky. It moves across the sky rapidly over the course of a night. The way the Moon looks to us is continually changing. Our Moon must travel a little farther in its path to make up for the added distance and complete its phase cycle. Why? In that time, as our Moon moves around Earth, the Earth also moves around the Sun. Moon fact: The Moon’s phases repeat every 29.5 days, but it’s orbit around the Earth only takes 27. Knowing how this dance between the Moon, Earth and Sun plays out lets us understand the Moon’s constantly changing appearance. But, as the Moon moves around the Earth, the face pointing towards us gradually becomes hidden from the Sun until we can hardly see it at all – this is a New Moon.And it appears to have phases because the amount of lunar surface bathed in sunlight we can see from Earth depends on where we and the Sun are. Once the face of the Moon is fully turned towards the Sun, it’s a Full Moon, and we see it all. When the Moon appears to be getting bigger, it’s ‘ waxing’ and when it looks like it’s getting smaller, it’s ‘ waning’. It takes the Moon 27.3 days to make a complete orbit around the Earth, but because the Earth is moving around the sun at the same time, it takes the moon 29.5 days to go through its eight different ‘phases’ – a lunar month.ĭid you know we have a FREE downloadable Phases of the Moon primary resource? Great for teachers, homeschoolers and parents alike! ![]() The Moon is Earth’s only natural satellite (a celestial body that orbits a planet). ![]() In actual fact, it’s just our view of it that’s altering… So, as the Moon orbits the Earth, the Sun lights up different parts of it, making it seem as if the Moon is changing shape. The Moon doesn’t emit (give off) light itself, the ‘ moonlight’ we see is actually the Sun’s light reflected off the lunar surface. Well, here’s the answer – it doesn’t ‘change shape’ at all! Let’s take a look at the phases of the Moon… Have you ever looked up at the sky and noticed how the Moon changes shape each night? Ever wondered why… And how? ![]()
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