Isaac Newton

Isaac Newton
1643-1727
*He suggested that a particle, if released, would spiral in to the center of the Earth. Hooke wrote back, claiming that the path would not be a spiral, but an ellipse.
http://scienceworld.wolfram.com/biography/Newton.html

Galileo Galilei

Galileo Galilei
1564-1642
*pioneered "experimental scientific method" and was the first to use a refracting telescope to make important astronomical discoveries
*discoveries using his new telescope

, including the moons of the planet Jupiter and the phases of the planet Venus (similar to those of Earth's moon).
*Galileo's observations with his new telescope convinced him of the truth of Copernicus's sun-centered heliocentric theory.
* Galileo's support for the heliocentric theory got him into trouble with the Roman Catholic. Sentenced to life imprisonment.
*
http://www.lucidcafe.com/library/96feb/galileo.html

Tycho Brahe

Tycho Brahe
1546-1601
* made a remarkable star catalogue of over 1000 stars
*He proved that comets are not objects in the atmosphere.
http://www.nada.kth.se/~fred/tycho/index.html

Copernicus

Copernicus
1473-1543
*Proposed that the Sun, not the Earth, was the center of the Solar System. Such a model is called a heliocentric system in the 16th century.
http://csep10.phys.utk.edu/astr161/lect/retrograde/copernican.html

Henrietta Leavitt

Henrietta Leavitt
1868-1921
*determine a star’s photographic brightness. Leavitt determined the absolute magnitude of about 47 stars near the North Pole. These stars were used as a standard to determine others stars’ brightness
http://pvastro0714.blogspot.com/2008/03/henrietta-swan-leavitt.html

James Van Allen

James Van Allen
1914-2006
* best known for discovering radiation belts encircling Earth
http://www.astronomy.com/asy/default.aspx?c=a&id=4452

Albert Michelson (Michelson-Morley experiment)

Albert Michelson (Michelson-Morley experiment)
1852-1931
* In 1878, began to work on confirming the existence of the mysterious "aether."
http://www.usd.edu/phys/courses/phys300/gallery/clark/mich.html

Pope Gregory XIII

Pope Gregory XIII
1502-1585
*changed the calendar in 1582
http://www.answers.com/topic/pope-gregory-xiii

Stephen Hawking

Stephen Hawking
1942-present
*In 1974 he decided to study the effects quantum mechanics might have on particles near a black hole. He theorized that particles are created in pairs, black and white for example. The black particle is absorbed by the black hole, the white particle, now without a partner, appears as radition.
http://www.hotliquidmagma.com/space/html/hawking.html

Carl Sagan

Carl Sagan
1934-1996
*He helped solve the mysteries of the high temperature of Venus, the seasonal changes on Mars and the reddish haze of Titan.
*Sagan was the author of many best sellers
http://www.mediamasters.com/sagan.htm

Ptolemy

Ptolemy
* approx. 87 to probably 170 AD.
*system of astronomy, written in his book the Syntaxis, was accepted until 1543
* used three mathematical constructions, the eccentric, epicycle, and equant, to account for the movements of the planets.
http://library.thinkquest.org/29033/history/ptolemy.htm

Hipparchus

Hipparchus
190-120 BCE
*Hipparchus made extensive observations of star positions, and is credited by some with the production of the first known catalogue of stars.
http://www.hps.cam.ac.uk/starry/hipparchus.html

Aristotle

Aristotle
384-322 BCE
*Aristotle argued that the universe is spherical and finite
*To prove that the earth is a sphere, he produced the argument that all earthly substances move towards the center, and thus would eventually have to form a sphere.
http://www.perseus.tufts.edu/GreekScience/Students/Tom/AristotleAstro.html