If you thought moon looked unusually large yesterday you were right(ish). But rather than having gotten closer it was the result of an optical illusion.

The moon illusion is a 'trick' whereby the solstice moon - as seen last night - looks bigger because it appears near the horizon, not because it is actually nearer.

NASA say the optical illusion is the result of lunar mechanics: "This week's high solstice sun gives us a low, horizon-hugging Moon and a strong Moon Illusion."

It was thought the Earth's atmosphere magnified the moon but according to NASA only humans 'see' the moon as larger because of our perception of the sky.

Because we are used to seeing clouds above us (a few miles away) and clouds on the horizon (hundreds of miles away) when we see the moon lower in the sky it seems further away and therefore bigger.