Question: why are there varying lengths of day and night?

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  1. Hi Fred,

    This is because the Earth is tilted on its axis. As it orbits the sun, a different part of the Earth faces it (not the equator). When the northern hemisphere faces the sun, we get shorter days. When the southern hemisphere faces the sun, we get longer days (and it’s daylight for 24 hours every day at the south pole!).


  2. Hi Fred, thats a really good question and Posty has answered with a great reason – because the earth is tilted.
    So, the earth turns on its own axis every 24 hours and it takes 365 days to orbit the sun (365.2425 days actually… which is why every 4 years we have a leap year and get an extra day) So as the earth moves around the sun, we get seasons depending on which part of the earth is tilted towards the sun at that time. This is also why the days a shorter in winter and longer in summer.

    If I had a super power I would make it summer all the time for me – I HATE the cold!


  3. Hi Fred,

    If you read David’s and Kate’s answers carefully and draw or imagine what this looks like, you’ll also see that summer days are longer (and winter days shorter) the farther you are from the equator (the closer to either the north pole or south pole you are). In cities ON the equator, such as Singapore, day and night are the same length all year round.

    Less well known is the fact that days are actually getting longer because the Earth’s rotation is slowing down (because of the moon and the sea tides it causes — bit complicated to explain how this works, though). The Earth is about 4,500 million years old. 620 million years ago, a bit before many kinds of advanced life appeared on Earth, the day was about 22 hours long rather than 24.