Thermal cameras detect the heat lost by a subject as infrared, but polar bears are experts at conserving heat. In space, light travels at 300,000 kilometres (186,000 miles) per second. Even at this breakneck speed, covering the 150 million odd kilometres (93 million miles) between us and the Sun takes a considerable time. And eight minutes is still very little compared to the five and a half hours it takes for the Sun’s light to reach Pluto.
