Herschel, the family name of three British astronomers.

Sir William Herschel

(1738-1822) was one of the greatest astronomers of all time. He was born in Hanover, Germany. In 1757 he came to England as a musician, but he devoted his spare time to astronomy. Herschel constructed a reflecting telescope in 1774, and in 1781 he discovered Uranusthe first planet discovered in historic times. He was made king's astronomer in 1782.

In 1783 Herschel deduced that the solar system is moving in relation to the stars and that it is moving in the direction of the constellation Hercules. After analyzing the distribution of the stars in the sky, Herschel concluded in 1785 that the sun lies within a huge disk-shaped system of stars. This system is today known as the Milky Way galaxy.

Herschel discovered numerous double stars and nebulae. During his extensive observations, he catalogued more than 800 double stars and 2,500 nebulae. He also discovered two satellites of Saturn and two of Uranus. In 1802 he noted that over the course of many years the component stars of several double-star systems appeared to be moving about each other. This discovery provided the first indication that Newton's law of gravitation extended beyond the solar system. In 1800 he discovered infrared radiation. Herschel was knighted in 1816.

Caroline Lucretia Herschel

(1750-1848) greatly assisted her brother William in his astronomical work. While making her own observations, she discovered several comets and nebulae. A revision she made of John Flamsteed's catalog of star positions was published in 1798.

Sir John Frederick William Herschel,

First Baronet (1792-1871), was the son of William Herschel. After attending Cambridge University he began reexamining his father's observations. During 1834-38 near Cape Town, South Africa, he charted the southern heavens. Herschel catalogued 2,100 double stars and 1,700 nebulae and star clusters. He was made a baronet in 1838.

Herschel was also an accomplished chemist and mathematician. Independently of William Henry Fox Talbot, he invented the process of photography on sensitized paper in 1839. Herschel also invented the blueprinting process, in 1842. He originated the terms positive and negative for photographic images. Herschel's most important contribution to photography was his discovery that sodium thiosulfate (hypo) would fix an image, preventing it from fading when exposed to light.