Herschel constructed his first large telescope in 1774, after which he spent nine years carrying out sky surveys to investigate double stars.

The resolving power of the Herschel telescopes revealed that many objects called nebulae in the Messier catalogue were actually clusters of stars.

Theories that they were Protestants from Bohemia have been questioned by Hamel as the surname Herschel already occurred a century earlier in the very same area in which the family lived.

Although his older brother Jakob had received his dismissal from the Hanoverian Guards, Wilhelm was accused of desertion[8] (for which he was pardoned by George III in 1782).

[13] Herschel moved to Sunderland in 1761; Charles Avison engaged him as the first violin and soloist for his Newcastle orchestra, where he played for one season.

He visited the home of Sir Ralph Milbanke at Halnaby Hall near Darlington in 1760,[14]: 14  where he wrote two symphonies, as well as giving performances himself.

[21][22] Herschel's reading in natural philosophy during the 1770s not only indicates his personal interests, but also suggests an intention to be upwardly mobile, both socially and professionally.

[22] Herschel took lessons from a local mirror-builder and having obtained both tools and a level of expertise, started building his own reflecting telescopes.

[36] In 1797, Herschel measured many of the systems again, and discovered changes in their relative positions that could not be attributed to the parallax caused by the Earth's orbit.

[44] He called the new planet the "Georgian star" (Georgium sidus) after King George III, which also brought him favour; the name did not stick.

[45][51][52] Caroline spent many hours polishing the mirrors of high performance telescopes so that the amount of light captured was maximized.

[55] She found fourteen new nebulae[56] and, at her brother's suggestion, updated and corrected Flamsteed's work detailing the position of stars.

Caroline has been referred to as a bitter, jealous woman who worshipped her brother and resented her sister-in-law for invading her domestic life.

Towards the end of her life, she arranged two-and-a-half thousand nebulae and star clusters into zones of similar polar distances.

This design was subject to chromatic aberration, a distortion of an image due to the failure of light of different component wavelengths to converge.

Optician John Dollond (1706–1761) tried to correct for this distortion by combining two separate lenses, but it was still difficult to achieve good resolution for far distant light sources.

Caroline Herschel described the pouring of a 30-foot-focal-length mirror: A day was set apart for casting, and the metal was in the furnace, but unfortunately it began to leak at the moment when ready for pouring, and both my brothers and the caster with his men were obliged to run out at opposite doors, for the stone flooring (which ought to have been taken up) flew about in all directions, as high as the ceiling.

[45][70] In 1789, shortly after this instrument was operational, Herschel discovered a new moon of Saturn: Mimas, only 250 miles (400 km) in diameter.

It inspired scientists and writers including Erasmus Darwin and William Blake, and impressed foreign tourists and French dignitaries.

[76] In 2012, the BBC television programme Stargazing Live built a replica of the 20-foot telescope using Herschel's original plans but modern materials.

The telescope was shown on the programme in January 2013 and stands on the Art, Design, and Technology campus of the University of Derby where it will be used for educational purposes.

[78] During Herschel's time, scientists tended to believe in a plurality of civilised worlds; in contrast, most religious thinkers referred to unique properties of the Earth.

Later in the 19th century, William Stanley Jevons proposed the 11-year cycle with Herschel's basic idea of a correlation between the low number of sunspots and lower yields explaining recurring booms and slumps in the economy.

[81] Herschel's speculation on a connection between sunspots and regional climate, using the market price of wheat as a proxy, continues to be cited.

[72][73] Herschel measured the axial tilt of Mars[86] and discovered that the Martian ice caps, first observed by Giovanni Domenico Cassini (1666) and Christiaan Huygens (1672), changed size with that planet's seasons.

[94][95][96][97] This heliocentric view was eventually replaced by galactocentrism due to the work of Harlow Shapley, Heber Doust Curtis and Edwin Hubble in the 20th century.

[102] On 8 May 1788, William Herschel married the widow Mary Pitt (née Baldwin) at St Laurence's Church, Upton in Slough.

[105] In 1816, William was made a Knight of the Royal Guelphic Order by the Prince Regent and was accorded the honorary title 'Sir' although this was not the equivalent of an official British knighthood.

[112] John Keats alludes to Herschel's discovery of Uranus in his 1816 sonnet "On First Looking into Chapman's Homer": "Then felt I like some watcher of the skies/ When a new planet swims into his ken."

"[113] His house at 19 New King Street in Bath, Somerset, where he made many telescopes and first observed Uranus, is now home to the Herschel Museum of Astronomy.