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If every human lined up facing north with their arms outstretched and touching, at what latitude would this closed circle be?

Robert Fizek,

Newton, Massachusetts, US

What would happen to a galaxy should the black hole at its centre 鈥渓eave鈥� for whatever reason?

Peter Bennett,

Hastings, New Zealand

To answer this question 鈥� or ask a new one 鈥� email lastword@newscientist.com.

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