Why is Europe's latest satellite called Herschel?
Sir William Herschel was one of the most innovative and successful astronomers of all time. Born in Hanover in 1738, he moved to London in 1757 and became a music teacher, singer and composer. In 1766 he moved to Bath in southwest England to take up a new job as an organist. It was here that he first became interested in astronomy and began experimenting and constructing his own mirrors and telescopes. In 1781, using one of his own telescopes and aided by his sister Caroline, he discovered the planet Uranus – the first planet discovered since prehistoric times. This brought his overnight fame and he was awarded a salary by the king, which allowed him to dedicate himself to astronomy full-time.
In 1800, he turned his attention to light and performed a simple experiment, the results of which explain why the Herschel Space Observatory has his name. He used a prism to split light into its constituent colours and using a thermometer took each one’s temperature. He discovered that the hottest light was the “invisible” one, which he called “calorific rays” – what is today known as infrared radiation, the light that Airbus Defence and Space’s mirror collects to produce its remarkable images of deep space.
When William Herschel died in 1822, he left behind a series of discoveries that changed the way space was seen. He had discovered Uranus, proved that nebulae were indeed groups of individual stars – many believed at the time that their milky appearance was due to a strange cosmic liquid – and discovered 2,500 nebulae and star clusters, as well as two moons of Uranus, Titania and Oberon, and two of Saturn’s moons, Mimas and Enceladus. These last two moons he found using the world’s largest and most powerful telescope – it had a 122-centimetre mirror and focal length of 12 metres – one he had built himself in 1789 thanks to a £4,000 grant from King George III.