An era of nighttime solar power is dawning in the U.S.
Tigers don't necessarily need huge dedicated reserves, say scientists, but can accommodate themselves to patterns of human activity by becoming more nocturnal.
Satellite images of city lights can be used to monitor outbreaks of disease, says a team led by Princeton University.
Solar Impulse has successfully completed its first night flight, the first solar-powered plane to do so.
The solar powered Impulse HB-SIA has successfully completed its maiden voyage over a picturesque Swiss airfield.