• Question: Why does the moon sometimes appear big?

    Asked by kylep to Adam, Chris, Eleanor, Jessamyn, Sinead on 18 Nov 2013.
    • Photo: Sinead Cullen

      Sinead Cullen answered on 18 Nov 2013:

      Awesome question,

      So as the moon orbits our little green planet, sometimes it can appear to be bigger than usual as it hangs in the sky.

      And the simple answer is that sometimes the moon is just closer to the earth than usual, and sometimes it is further away. At certain times of the year the moon can be much closer to earth and can lead to what is known as a Super full moon (which looks amazing). The average distance between the earth and the moon is about 382,000 kilometers, but this can vary by nearly 50,000 kilometers! There are calculators online too that can help you find out what time of the year the moon is due to be the closest to earth.

      A great night for this is Christmas eve, you could crack out the telescope and use the calculator and see you never know who you might see or even calculate his time of arrival??

      Hope this helps 🙂

    • Photo: Adam Murphy

      Adam Murphy answered on 18 Nov 2013:

      Hey Kyle,

      I actually have to disagree with Sinead here (sorry!)

      The Moon does come closer and further away but that’s not the main reason.

      It’s an optical illusion called the Moon Illusion. When the Moon is closer to the ground it appears bigger. You can stretch out your thumb and measure the size to see that it hasn’t really gotten any bigger.

      How the Moon illusion works is still debated. Some say it’s because it looks bigger when it’s beside buildings and things, but when it’s on it’s own you’ve nothing to compare it to. So your brain says it’s smaller.

      There’s also an idea to do with clouds. Clouds appear to be smaller as they get towards the horizon (get further away from us). So our brain gets confused when the Moon doesn’t do that, so we think of it as bigger (because our brains work by trying to make patterns).

      Nobody really agrees on why it’s true. It’s so weird!

    • Photo: Eleanor Holmes

      Eleanor Holmes answered on 20 Nov 2013:

      Hey guys,

      Another optical illusion that can make objects in the sky appear bigger is when there is less water vapour in the atmosphere getting in the way of the light the moon can appear brighter, which in turn makes it look bigger than a dull moon.

      But it’s mostly the perspective thing. When it’s easier for our brain to compare sizes, we see things for how they are.

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