ancient astronomers timeline

1656, 1659, 1665, 1678 AD

1543 AD

Christiaan Huygens

Nicholas Copernicus

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

In 1783, Herschel discovers the speed and direction of the Sun's motion. He analyzed the motions of 7 bright stars and showed that part of their motions was due to the motion of the Sun through space.

Copernicus was a Reneissance-era mathematician and astronomer. He often questioned the astronomy of his age, like Ptolemy's theory of an earth-centered solar system.

Galileo Galilei

1600, 1609, 1610, 1632 AD

In 1785, Herschel uses star counts to map the Milky Way. He assumes the galaxy extends farther in directions in which he could see more stars. He also found the galaxy to be flattened with the Sun near the middle.

Giuseppe Piazzi

1801 AD

Herschel shows many double stars are binaries and finds thatfor many pairs of stars, the orientation of the two stars change with time as a result of orbital motion.

Galileo was an Italian astronomer, physicist, and engineer. He has been called the father of observational astronomy, modern physics, and modern science.

Herschel was a German-born British astronomer, composer, and brother of fellow astronomer Caroline Herschel.

Copernicus publishes "De Revolutionibus", describing his heliocentric model of the solar system. Most of his theories and observations were not proven until the 1600s.

In 1656, Huygens discovers that Saturn's "appendages" are actually rings. He also discovers Titan, Saturn's fourth moon. Later, in 1659, Huygens notes markings on Mars. In 1665, he watches Saturn's rings "disappear" and reappear several years later.

Piazzi was an Italian Catholic priest, mathematian, and astronomer. He established an observatory at Palermo, now the Osservatorio Astonomico di Palermo.

250 BC

In 1600, Galileo begins ecperiements with falling and rolling bodies. His experiements lead him to conclude that once something is set in motion, it will remain in motion until something stops it.

1783, 1785, 1801 AD

Eratosthenes

William Herschel

In 1609, he finds that the Moon has mountains, valleys, and plains like the Earth.

Born in Cyrene, Libya, Eratosthenese was a Greek scientific writer, astronomer, and poet. He made the first measurement of the size of the Earth for which the details are known.

In 1610, he observes the phases of Venus and discovers four of Jupiter's moons. His observation of Venus' phases was incompatible with Ptolemy's geocentric model of the solar system.

At his observatory, Piazzi produced a catalog of 7,646 stars and demonstrated that most stars are in motion relative to the Sun. In 1801, he discovered the first asteroid, Ceres.

1665-7, 1678, 1686 AD

Issac Newton

Tycho Brahe

134 BC

1572 AD

Hipparchus

Eratosthenes observed that the Sun's rays in Syene (now Aswān) fell vertically at noon on the summer solstice. He found that on the same date and time in Alexandria, sunlight fell about 7.2° from vertical. Estimating the distance between the two cities, he was able to calculate the Earth's circumference to be about 24,660 miles. He was only about 211 miles off.

Newton was an English mathematician, physicist, astronomer, theologian, and author who is widely recognized as one of the most influential scientists of all time. He was a key figure in the scientific revolution.

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

Hipparchus was a Greek astronomer, geographer, and mathematician. He is considered the founder of trigonometry.

In 1665, Newton discovers the law of universal gravitation. Over the next 2 years, he made fundamental discoveries in optics and invented differential and integral calculus.

In 1572, Brahe discovers a supernova in the constellation of Cassiopeia. His book of observations establishes his reputation as an astronomer. He later creates his own geocentric model of the solar system.

When Huygens proposes that light consists of waves in 1678, Newton disputed this, saying light was made up of a stream of particles.

Hipparchus discovered precession, and he prepares a stellar catalogue. He compared his observations with earlier ones to discover precession, the slow change in the direction of the Earth's polar axis. He also created what was likely the first catalogue of star positions, recording over 850 stars' positions and their brightness.

In 1686, Newton publishes "Principia". His work describes his discoveries about gravity, motion, and the orbits of the planets.

1604, 1610 AD

Johannes Kepler

Kepler was a German astronomer, mathematician, and astrologer. He was a key figure in the 17th centuty scientific revolution.

In 1604, Kepler observes a supernova with extensive naked-eye observations.

In 1610, Kepler discovers the laws of planetary motion. While working with Tycho Brahe's observations, Kepler discovers the shapes of planetary orbits, how the speed of a planet varies as it orbits the Sun, and the

relationship between orbital distance and

orbital period.

Ancient Astronomers Timeline

Clara Mitchell