The behaviour of water in the atmosphere is a poorly understood part of the hydrological cycle. Applying the principles of isotope chemistry to satellite data provides a powerful approach for improving the situation.

Which end of a fly embryo becomes the head is partly dictated by the accumulation of bicoid RNA at the anterior pole. The protein that amasses the RNA turns out to be an old acquaintance from a different context.

Electrical circuits might be regarded as rather mundane pieces of classical engineering. But their electromagnetic fields are, like light, a quantum object whose energy comes in discrete units — photons.