What is a 'pink rainbow', and why does it happen?

A pink rainbow lit up the sky on Monday evening.

The rare sight was spotted in Dorset, Somerset and other parts of the UK.

A pink rainbow

A pink rainbow

Rainbows that appear at sunrise and sunset appear pink because the sun is lower in the sky.

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The optical illusion is caused when the colours at the red end of the spectrum are the only ones to be refracted - making the rainbow appear pink.

Angela Taylor spotted the rainbow above Marie Road in Dorchester.

She said: "It was absolutely beautiful. I've never seen anything like it.

"I thought to myself, this world can be such an ugly place, and then you see something like this."