This week's new questions

At any one time, how much of Earth is covered by cloud? Does this vary? Andrew Parsons, Welford, Northants, UK

I notice the smell of perfume I have used for a while less than a new one. Is our sense of new smells keener? What’s the evolutionary benefit of this? Chloe Hurst, Leeds, UK

To answer these questions – or ask a new one – email lastword@newscientist.com.

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