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Last Word is Â鶹´«Ã½â€™s long-running series in which readers give scientific answers to each other’s questions, ranging from the minutiae of everyday life to absurd astronomical hypotheticals. To answer a question or ask a new one, email lastword@newscientist.com
Why do we itch in random places? What makes this impulse manifest on, say, an elbow at one moment, but the back of a knee at another?
Rachel Loden,
California, US
Adam Burton/Alamy
Why do rainbows refract light into several different colours, but we don’t see the same effect with cloud inversions?
Tony Sandy,
Alness, the Highlands, UK
To answer this question – or ask a new one – email lastword@newscientist.com.
Questions should be scientific enquiries about everyday phenomena, and both questions and answers should be concise. We reserve the right to edit items for clarity and style. Please include a postal address, daytime telephone number and email address.
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