Astronomy - Early Famous Astronomers





Early Famous Astronomers


Ptolemy AD100-170

Claudius Ptolemy was a Greco-Roman mathematician, astronomer, geographer, astrologer, and poet. He lived in the city of Alexandria in the Roman province of Egypt, wrote in Greek, and held Roman citizenship.

Ptolemy's Almagest is the only surviving comprehensive ancient treatise on astronomy.

Ptolemy derived his geometrical models from selected astronomical observations by his predecessors spanning more than 800 years, though astronomers have for centuries suspected that his models' parameters were adopted independently of observations.

Ptolemy presented his astronomical models in convenient tables, which could be used to compute the future or past position of the planets.

His Planetary Hypotheses went beyond the mathematical model of the Almagest to present a physical realization of the universe as a set of nested spheres, in which he used the cycles of his planetary model to compute the dimensions of the universe.

He estimated the Sun was at an average distance of 1,210 Earth radii, while the radius of the sphere of the fixed stars was 20,000 times the radius of the Earth.


Nicolaus Copernicus 1473-1543

Nicolaus Copernicus was born on 19 February 1473 in the city of Thorn, in the province of Royal Prussia, in the Crown of the Kingdom of Poland.

His father was a merchant from Kraków and his mother was the daughter of a wealthy merchant.

He was a Renaissance-era mathematician and astronomer he obtained a doctorate in canon law and was also a physician, classics scholar, translator, governor, diplomat, and economist.

Who formulated a model of the universe that placed the Sun rather than the Earth at the center of the universe.


Tycho Brahe 1546-1601

Tycho Brahe was a Danish nobleman, astronomer, and writer known for his accurate and comprehensive astronomical and planetary observations.

He was born in the then Danish peninsula of Scania. Well known in his lifetime as an astronomer, astrologer and alchemist, he has been described as "the first competent mind in modern astronomy to feel ardently the passion for exact empirical facts.

Tycho worked to combine what he saw as the geometrical benefits of the Copernican system with the philosophical benefits of the Ptolemaic system into his own model of the universe, the Tychonic system. His system correctly saw the Moon as orbiting Earth, and the planets as orbiting the Sun, but erroneously considered the Sun to be orbiting the Earth. Furthermore, he was the last of the major naked-eye astronomers, working without telescopes for his observations.

On 11 November 1572, Tycho observed a very bright star, now numbered SN1572, which had unexpectedly appeared in the constellation Cassiopeia.

In 1573, he published a small book, De nova stella thereby coining the term nova for a "new" star (we now classify this star as a supernova and we know that it is 7,500 light-years from Earth).



Johannes Kepler 1571-1630 

Johannes Kepler was a German mathematician, astronomer, and astrologer.

Kepler is a key figure in the 17th-century scientific revolution.

He is best known for his laws of planetary motion. These works also provided one of the foundations for Isaac Newton's theory of universal gravitation.

Kepler was a mathematics teacher at a school in Graz. Later he became an assistant to the astronomer Tycho Brahe in Prague, and eventually the imperial mathematician to Emperor Rudolf II. He also taught mathematics in Linz.

Additionally, he did fundamental work in the field of optics, invented an improved version of the refracting telescope (the Keplerian telescope), and was mentioned in the telescopic discoveries of his contemporary Galileo Galilei.


Christiaan Huygens 1629-1695

Christiaan Huygens was a Dutch physicist, mathematician, astronomer and inventor, who is widely regarded as one of the greatest scientists of all time and a major figure in the scientific revolution.

In physics, Huygens made ground breaking contributions in optics and mechanics, while as an astronomer he is chiefly known for his studies of the rings of Saturn and the discovery of its moon Titan.

As an inventor, he improved the design of the telescope with the invention of the Huygenian eyepiece. His most famous invention, however, was the invention of the pendulum clock in 1656, which was a breakthrough in timekeeping and became the most accurate timekeeper for almost 300 years. Because he was the first to use mathematical formulae to describe the laws of physics, Huygens has been called the first theoretical physicist and the founder of mathematical physics.



Cassini was an astronomer at the Panzano Observatory, from 1648 to 1669. He was appointed professor of astronomy at the University of Bologna in 1650 and became, in 1671, director of the Paris Observatory.

He thoroughly adopted his new country, to the extent that he became interchangeably known as Jean-Dominique Cassini.

Cassini observed and published surface markings on Mars (earlier seen by Huygens but not published), determined the rotation periods of Mars and Jupiter, and discovered four satellites of Saturn.

In addition he discovered the Cassini Division in the rings of Saturn (1675). He shares with Robert Hooke credit for the discovery of the Great Red Spot on Jupiter (ca. 1665). Around 1690, Cassini was the first to observe differential rotation within Jupiter's atmosphere.



Sir Isaac Newton 1642-1726

Sir Isaac Newton was an English mathematician, astronomer, and physicist (described in his own day as a "natural philosopher") who is widely recognised as one of the most influential scientists of all time and a key figure in the scientific revolution.

Newton was a fellow of Trinity College and the second Lucasian Professor of Mathematics at the University of Cambridge.

He was a devout, but unorthodox, Christian who privately rejected the doctrine of the Trinity.

Unusually for a member of the Cambridge faculty of the day, he refused to take holy orders in the Church of England.

His book Mathematical Principles of Natural Philosophy, first published in 1687, laid the foundations of classical mechanics.

Newton also made seminal contributions to optics, and shares credit with Gottfried Wilhelm Leibniz for developing the infinitesimal calculus.

In Principia, Newton formulated the laws of motion and universal gravitation that formed the dominant scientific viewpoint until it was superseded by the theory of relativity.

Newton used his mathematical description of gravity to prove Kepler's laws of planetary motion, account for tides, the trajectories of comets, the precession of the equinoxes and other phenomena, eradicating doubt about the Solar System's heliocentricity.

Newton built the first practical reflecting telescope and developed a sophisticated theory of colour based on the observation that a prism separates white light into the colours of the visible spectrum.

Politically and personally tied to the Whig party, Newton served two brief terms as Member of Parliament for the University of Cambridge, in 1689–90 and 1701–02.

He was knighted by Queen Anne in 1705 and spent the last three decades of his life in London, serving as Warden (1696–1700) and Master (1700–1727) of the Royal Mint, as well as president of the Royal Society (1703–1727).


Edmond Halley 1656-1742

Edmond Halley was an English astronomer, geophysicist, mathematician, meteorologist, and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720.

Halley was born in Haggerston, in east London. His father, Edmond Halley Sr., came from a Derbyshire family and was a wealthy soap-maker in London.

As a child, Halley was very interested in mathematics. He studied at St Paul's School where he developed his initial interest in astronomy, and from 1673 at The Queen's College, Oxford. While still an undergraduate, Halley published papers on the Solar System and sunspots.

From an observatory he constructed on Saint Helena, Halley recorded a transit of Mercury across the Sun.

He realised a similar transit of Venus could be used to determine the size of the Solar System. He also used his observations to expand contemporary star maps.

He aided in observationally proving Isaac Newton's laws of motion, and funded the publication of Newton's influential book.

From his September 1682 observations, he used the laws of motion to compute the periodicity of Halley's Comet in his 1705 Synopsis of the Astronomy of Comets. It was named after him upon its predicted return in 1758, which he did not live to see.


Frederick William Herschel 1738-1822

Frederick William Herschel was a German-British astronomer, composer and brother of fellow astronomer Caroline Herschel, with whom he worked.

Born in the Electorate of Hanover, Herschel followed his father into the Military Band of Hanover, before migrating to Great Britain in 1757 at the age of nineteen. His works were praised by Mozart, Haydn (who met Herschel in London) and Beethoven.

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 the nebulae in the Messier catalogue were clusters of stars. Herschel published catalogues of nebulae in 1802 (2,500 objects) and in 1820 (5,000 objects).

In the course of an observation on 13 March 1781, he realized that one celestial body he had observed was not a star, but a planet, Uranus. This was the first planet to be discovered since antiquity and Herschel became famous overnight.

As a result of this discovery, George III appointed him Court Astronomer. He was elected as a Fellow of the Royal Society and grants were provided for the construction of new telescopes.

The largest and most famous of Herschel's telescopes was a reflecting telescope with a 49 1⁄2-inch-diameter (1.26 m) primary mirror and a 40-foot (12 m) focal length.

The 40-foot telescope was, at that time, the largest scientific instrument that had been built. It was hailed as a triumph of "human perseverance and zeal for science"

In 1785 Herschel approached King George 111 for money to cover the cost of building the 40-foot telescope. He received £4,000. Without royal patronage, the telescope could not have been created. As it was, it took five years, and went over budget.


Charles Messier 1730-1817

Charles Messier was a French astronomer most notable for publishing an astronomical catalogue consisting of 110 nebulae and star clusters, which came to be known as the Messier objects.

The purpose of the catalogue was to help astronomical observers, in particular comet hunters like himself, distinguish between permanent and transient visually diffuse objects in the sky.

Messier was born in the Lorraine region of France, being the tenth of twelve children. Six of his brothers and sisters died while young and in 1741, his father died.

Charles' interest in astronomy was stimulated by the appearance of the spectacular, great six-tailed comet in 1744 and by an annular solar eclipse visible from his hometown on 25 July 1748.

Messier's first documented observation was that of the Mercury transit of 6 May 1753, In 1764, he was made a fellow of the Royal Society, in 1769 he was elected a foreign member of the Royal Swedish Academy of Sciences, and on 30 June 1770, he was elected to the French Academy of Sciences.


Caroline Lucretia Herschel 1750-1848

Caroline Lucretia Herschel was a German astronomer, whose most significant contributions to astronomy were the discoveries of several comets, including the periodic comet 35P/Herschel–Rigollet, which bears her name.

She was the younger sister of astronomer William Herschel, with whom she worked throughout her career.

She was the first woman to be awarded a Gold Medal of the Royal Astronomical Society (1828), and to be named an Honorary Member of the Royal Astronomical Society 1835.

Following the death of their father, William suggested that Caroline join him in Bath England. In 1772 Caroline was first introduced to astronomy by her brother.

Caroline spent many hours polishing the mirrors of high performance telescopes so that the amount of light captured was maximized.

She also copied astronomical catalogues and other publications for William. After William accepted the office of King's Astronomer to George III, Caroline became his constant assistant.

With Edward C. Pickering, she is credited with the creation of the Harvard Classification Scheme, which was the first serious attempt to organize and classify stars based on their temperatures and spectral types.

She was nearly deaf throughout her career. She was a suffragist and a member of the National Women's Party.