William Herschel: Discoverer of Uranus and Pioneer of Stellar Astronomy

From Musical Origins to Astronomy

Born on November 15, 1738 in Hanover (Germany) into a musical family, Friedrich Wilhelm Herschel (1738-1822) emigrated to England in 1757 to escape the Seven Years' War. He first became a professional musician (cellist and composer) before developing a passion for astronomy at age 35.

Self-taught, he studied the works of:

• Isaac Newton (1643-1727) for optics
• James Ferguson (1710-1776) for practical astronomy
• John Michell (1724-1793) for gravitation

He built his own telescopes and became a master in making parabolic mirrors.

The Discovery of Uranus (1781) and Recognition

On March 13, 1781, Herschel observed what he thought was a comet in the constellation Gemini. After months of observation, he realized he had discovered a new planet:

• First planet discovered since antiquity (beyond Saturn)
• Named Uranus in 1783 (proposed by Johann Bode)
• This discovery earned him:
  • The Copley Medal from the Royal Society (1781)
  • A position as astronomer to King George III (1782)
  • An annual pension of £200 to continue his research

He initially proposed naming the planet "Georgium Sidus" in honor of the king, but the scientific community eventually adopted "Uranus".

Major Contributions to Astronomy

Herschel revolutionized several fields of astronomy:

1. Stellar Astronomy

He established the foundations of modern star studies:

• First systematic catalog of nebulae (1786, 1789, 1802) with 2,500 objects
• Discovery of binary stars (1802) and demonstration of their orbital motion
• Theory of the Milky Way structure (1785) as a flattened disk

2. Telescope Construction

He designed revolutionary instruments:

• 48-inch (1.2 m) reflector telescope in 1789, the world's largest for 50 years
• Technique for polishing speculum metal mirrors (77% copper, 23% tin)
• Invention of the front view to avoid aberrations

3. Discovery of Infrared Radiation

In 1800, he accidentally discovered infrared rays while studying solar light dispersion:

• First detection of light beyond the visible spectrum
• Used a thermometer to measure heat from different colors
• Foundation of infrared spectroscopy

Legacy and Posterity

Herschel left an immense scientific legacy:

• Foundation of extragalactic astronomy (his nebula catalogs were used by Edwin Hubble)
• Influence on John Herschel (1792-1871), his son, who continued his work
• Coined the term "asteroid" (1802) for small celestial bodies
• Discovery of two moons of Uranus (Titania and Oberon, 1787) and two moons of Saturn

He died on August 25, 1822 in Slough (England) and was buried at Westminster Abbey. His 48-inch telescope is now displayed at the Science Museum (new window) in London.