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Period: Jan 1, 1500 to
Timeline of Astronomers from 1500 to 1750
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Jan 1, 1508
Nicolaus Copernicus
By 1508, Copernicus had begun developing his own celestial model, of a heliocentric planetary system. Copernicus's heliocentric solar system named the sun, rather than the earth, as the center of the solar system. Copernicus believed that the size of each planet's orbit depended on its distance from the sun. -
Jan 1, 1577
Tycho Brahe
In 1577 Brahe proved that the supernova never changed with regard to the surrounding stars, and that the comet orbited beyond the path of the moon. Brahe didn't like Coppernicus's sun-centered model, so he came up with a new model that combined his model and Copernicus's model. He set the moon and sun in orbit around the Earth even as the other five known planets circled the sun. -
Johannes Kepler
Kepler's laws of planetary motion were published in 1609. Kepler claimed that gravity was caused by two bodies, rather than one, and that the moon was the cause of the motion of tides on the Earth. In recognition of his contribution to our understanding of the motion of the planets, NASA named their planet-finding telescope after Kepler. -
Thomas Harriot
In 1610 Harriot became the first Westerner to observe sunspots through a telescope. Harriot made advances in algebra and optics. He also discovered Snell's law of refraction before Snell did. -
Galileo Galilei
In 1609, Galileo learned about a simple telescope built by Dutch eyeglass makers, and he soon developed one of his own. 1610, he published a small booklet called The Starry Messenger, revealing his discoveries that the moon was not flat and smooth, but a sphere with mountains and craters. He also discovered Jupiter had revolving moons, that didn’t revolve around the earth. -
Christiaan Huygens
In 1654 Huygens came up with a better method of grinding and polishing the lenses of telescopes, providing greater clarity. He turned one of his improved telescopes toward the planet Saturn and determined that Saturn was a ringed planet. Huygens also discovered a large moon orbiting the planet, which he named Titan. -
Isaac Newton
Around the mid 1660s Newton did a number of experiments on light, discovering that white light is made of the same system of colors that can be seen in a rainbow. This established the modern study of optics. Newton was appointed second Lucasian professor of mathematics. It was Newton's reflecting telescope, made in 1668, that finally brought him to the attention of the scientific community. -
Giovanni Cassini
In 1675 Cassini was the first to observe four of Saturn's moons. Cassini was also the first to observe the different rotations within Jupiter's atmosphere. The Cassini Orbiter is the fourth space probe to visit Saturn and the first to enter orbit. -
Edmond Halley
In 1678 Halley had recorded the celestial longitudes and latitudes of 341 stars and observed a transit of Mercury across the Sun's disk. His star catalogue was the first to contain telescopically determined locations of southern stars. In the same year he was elected a fellow of the Royal Society. -
James Bradley
Bradley measured the diameter of Venus with a telescope over 212 feet in length. Bradley observed the star γ Draconis, hoping to discover the parallactic motion of the stars, a seeming change in the positions of the stars, scattered through space. Bradley also observed a full cycle of the motion of the moon's nodes.
