If you have the right type of band-aid, it may emit visible blue light. The phenomenon can also be seen if you unfurl adhesive tape, crush a sugar cube in the dark, or when watching an avalanche ...

ARRIVING at the remote village school in the Tigray highlands, Band Aid icon Birhan Woldu is swamped by a sea of smiling faces. At the head of the crowd, two beaming children are holding a sign ...