Why does the moon change phases

Jane Green is an astronomy writer and speaker, and author of the Haynes Astronomy Manual. Home Science Why does the Moon have phases? The phases of the Moon. The inner circle shows what the Moon looks like seen from above its north pole, while the outer circle shows the phase we see from Earth at that time.

Credit: Sarah and Simon Fisher. Credit: Paul Licorish. Credit: Harvey Scoot. Full Moon at Perigee by Tom Howard. Credit: Andrew McNaught. Lunar libration. Credit: Pete Lawrence. It takes 27 days, 7 hours, and 43 minutes for our Moon to complete one full orbit around Earth.

However, it takes our Moon about This is called the synodic month. The difference between the sidereal and synodic months occurs because as our Moon moves around Earth, the Earth also moves around our Sun. Our Moon must travel a little farther in its path to make up for the added distance and complete the phase cycle. What is the dark side of the Moon? In spite of the phrase, there actually is no dark side of the Moon! Just like Earth, our Moon rotates on its own axis and experiences daylight and dark cycles.

Our Moon's day and night cycles are a little longer than Earth's — the Moon spins on its axis once every Our Moon's period of rotation matches the time of revolution around Earth. In other words, it takes our Moon the same length of time to turn once on its axis as it takes it to go once completely around the Earth!

Do other planets have moons? Several of the planets in our solar system have natural satellites that orbit them. Some are so recently discovered that they have not yet been named. Mars has Phobos and Deimos, two small moons that circle very close to the martian surface. Jupiter has more known satellites than any other planet — 61! Saturn has at least 31 satellites, Uranus has 27, and Neptune has 13 — and more are being discovered all the time! Pluto has one moon — Charon — the largest moon with respect to the size of the planet it revolves around.

The Moon displays these eight phases one after the other as it moves through its cycle each month. It takes 27 days for the Moon to orbit Earth. That means the Moon's cycle is 27 days long. Use this tool to see the current Moon phase and to plan ahead for other Moon views. Credit: NASA. The Short Answer:. We have a slightly different view of the Moon each night. What Is a Solar Eclipse?

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