-
Feb 19, 1473
Nicolaus Copernicus
Nicolaus was the first to propose that the planets revolved around the Sun in the Copernican Model; thus, he concluded Earth was not the center of the Universe. Furthermore, he determined Earth's movement in space caused Retrograde motion where planets would sometimes move backwards in the sky. Finally, Nicolaus suggested Earth's rotation caused the movement of the Sun and the stars as Earth's revolution around the Sun was responsible for the seasons. -
Dec 14, 1546
Tycho Brahe
Tycho Brahe is most known for designing and building instruments as well as consistently calibrating and checking thier accuracy. In 1572, he observed the "Tycho's Supernova" and observed the new star found in Cassiopeia. Different from the Copernican and Ptolemaic models, Brahe formed a solar system with Earth as the center that the most accepted at the time. -
Feb 15, 1564
Galileo Galilei
Galileo is most known for significantly improving his telescopes as they had a magnification of eight or nine. With his strong telescopes, Galileo discovered four moons of Jupiter, including Io, Ganymede, Europa, and Callisto. Other observations of Galileo are the phases of Venus, sunspots, and craters on the moon. -
Dec 27, 1571
Johannes Kepler
Johannes Kepler is commonly known for Kepler's Laws on Planetary Motion. His three laws stated that the planet's travel in elliptical paths, an invisible line connecting the planet to the Sun covered an equal amount of area over an equal amount of time, and the time it takes planets to orbit the Sun is connected to its distance from the Sun. Kepler also stated that gravity was caused by two bodies and not one as the Moon caused the tides. -
John Baptist Riccioli
Riccioli was the first astronomer to discover a star in visual binary, Mizar, which are "two optically distinguished components revolving around each other." He also wrote the encyclopedia, "Almagestum Novum," in which had an advanced lunar map. His telescopic study of the Moon was greatly detailed and is an important component of astronomical studies. -
Giovanni Cassini
Cassini was the first astronomer to observe Saturn's moons, including Rhea, Lapetus, Tethys, and Dione. In addition, he was also the first to estimate the dimensions in the solar system using parallax to find the distance between Earth and Mars. Finally, Cassini shares credit in discover the Grea Red Spot on Jupiter, and he observed the Cassini division in Saturn's rings and the rotation in Jupiter's atmosphere. -
Christiaan Huygens
Huygens was the first to notice that Saturn's elongated shape represented its rings. Furthermore, Huygens also discovered Saturn's large moon, Titan. Additionally, he proposed laws of refraction and reflection. -
Sir Issac Newton
Sir Issac Newton is most known for writing the Laws of Motion for the Universe. The three laws include information that objects move at the same velocity unless an outside force acts upon it, a force acting on an object is equal to the object’s mass times the acceleration it undergoes, and every action has an equal and opposite reaction. Additionally, Newton also invented the reflecting telescope that produced a sharper image. -
Edmond Halley
Edmond Halley's most popular observation was of "Halley's Comet" that he found revolved around the Sun every 75 years. However, Halley also published papers involving the solar system and sunspots. He studied the variation between Earth's True North and Magnetic North. Lastly, Halley determined the distance between the Earth and the Sun by tracting the transits of Venus. -
Charles Messier
Charles Messier created the Messier Catalog that contained observations of nebulous objects in the Northern Hemisphere. In 1758, Charles discovered the first object in his catalog named Messier 1, or Crab Nebula. Other popular entries included Andromeda Galaxy (M31), Orion Nebula(M42 & M43), and Pleiades (M45). Throughout his career, Messier was able to discover forty nebulae and thirteen comets.
