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Moonrise delay

Why does moonrise get later each night?

The Moon moves east along its orbit while Earth turns. Earth has to spin extra — about 50 minutes — to bring the Moon back to the same place on your sky. That extra is why moonrise (and moonset) slip later day by day.

After one Earth turn the Moon has advanced. The ground must turn farther to find it again.

The same 50 minutes as the month

A synodic month is about 29.5 days. Spread that extra lap around the sky over 24 hours and you get roughly 50 minutes. The delay is not a separate mystery. It is the month, counted per night.

See it live

On the hub: Moon · Sun–Earth–Moon simulator

Related questions

What is a synodic month? A synodic month is the time from one full moon to the next, about 29.5 days. It is longer than the Moon’s trip around Earth relative to the stars, because Earth has moved and the Moon must catch up to the same angle with the Sun.

Why does the Moon change shape? The Moon makes no light of its own. One half is always lit by the Sun. Phases are your changing view of that lit half as the Moon goes around Earth — about 29.5 days from full moon to full moon.

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