Why do we need leap years?

The Earth takes about 365.25 days to complete an orbit around the Sun (one year). If you just round the calendar year down to the nearest whole number, the date recorded by the calendar will drift out of sync with the seasons.

What colour is a mirror?

In white light, which includes the wavelengths of the visible spectrum, the colour of an object is dictated by those wavelengths of light that its surface atoms fail to mop up. As a perfect mirror reflects back all the colours comprising white light, it’s also white.

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Top 5 Richard Feynman books

The Nobel prize-winning physicist Richard Feynman would have celebrated his 95th birthday this week. To coincide with the new BBC documentary The Fantastic Mr Feynman, the editor of Focus magazine, Graham Southorn, selects his favourite Feynman books.

Top 7 science superpowers

The international landscape of science is changing. The rapid growth of scientific output from emerging economic powers, especially China, could re-draw the map.