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322 BCE
Aristotle
Aristotle's lifespan was 384-322 BC. The influence of Aristotle's work on the physical sciences spread far and wide, offering well thought out theory and reasoning that would prevail for many years to come before eventually being replaced by modern physics.. He studied under the great philosopher Plato and later started his own school, the Lyceum at Athens. He, too, believed in a geocentric Universe and that the planets and stars were perfect spheres though Earth itself was not. -
168
Ptolemy
Ptolemy was an astronomer and mathematician who lived from 100-168 AD. He also believed that the earth was the center of the Universe. -
May 24, 1543
Copernicus
Copernicus was born 2/19/1473 and died 5/24/1543.Copernicus finished the first manuscript of his book, "De Revolutionibus Orbium Coelestium" ("On the Revolutions of the Heavenly Spheres") in 1532. In it, Copernicus established that the planets orbited the sun rather than the Earth. He laid out his model of the solar system and the path of the planets. -
Tycho Brahe
Tycho Brahe was a Danish astronomer and nobleman. He believed in the idea of a geocentric universe, a universe with Earth at its center.This is in opposition of Copernicus' who believed in the sun as the center of the universe. -
Hans Lippershey
Hans Lippershey is a German-Dutch spectacle-maker. He is commonly associated with the invention of the telescope, because he was the first one who tried to obtain a patent for it. It is, unclear if he was the first one to build a telescope. -
Johannes Kepler
Johannes Kepler lived from 12/27/1571 to 11/15/1630 was a German astronomer, who discovered three major laws of planetary motion, conventionally designated as follows:1. the planets move in elliptical orbits with the Sun at one focus;2. the time necessary to traverse any arc of a planetary orbit is proportional to the area of the sector between the central body and that arc (the “area law”); and 3. there is an exact relationship between the squares of the planets’. -
Galileo
Using his telescope, Galileo made many observations of our Solar System. He came to believe that the idea that the Sun and other planets orbited around the Earth was not correct. Galileo felt that an astronomer named Copernicus had a better idea. Copernicus believed the Earth and other planets moved around the Sun. -
Giovanni Cassini
Giovanni Cassini was an Italian mathematician, astronomer, and engineer born 6/8/1625 and died 9/14/1712, who discovered four satellites of Saturn and noted the division of the rings of Saturn which are the most extensive planetary ring system of any planet in the Solar System. -
Sir Isaac Newton
Sir Isaac Newton contributed significantly to the field of science over his lifetime. He invented calculus and provided a clear understanding of optics. But his most significant work had to do with forces, and specifically with the development of a universal law of gravity. -
William Herschel
Sir William Herschel was a German-born British astronomer and composer, who is widely credited as the founder of sidereal astronomy for observing the heavenly bodies. He found the planet Uranus and its two moons, and formulated a theory of stellar evolution. -
Percival Lowell
Percival Lowell, born March 13, 1855, died Nov. 12, 1916. American astronomer who predicted the existence of a planet beyond the orbit of Neptune and initiated the search that ended in the discovery of Pluto. -
Sputnik
Sputnik was the first artificial Earth satellite. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957, orbiting for three weeks before its batteries died, then silently for two more months before falling back into the atmosphere. -
Karl Jansky
Karl Jansky was an astronomer born October 22, 1905, and died February 14, 1950. He first discovered radio waves emanating from the Milky Way. He is considered one of the founding figures of radio astronomy. -
Edwin Hubble
Edwin Hubble was born November 20, 1889, and died September 28, 1953, and Edwin Hubble played a pivotal role in deciphering the vast and complex nature of the universe. His meticulous studies of spiral nebulae proved the existence of galaxies other than our own Milky Way. -
Albert Einstein
Einstein was born March 14, 1879 and died April 18, 1955 A major validation of Einstein's work came in 1919, when Sir Arthur Eddington, secretary of the Royal Astronomical Society, led an expedition to Africa that measured the position of stars during a total solar eclipse. The group found that the position of stars was shifted due to the bending of light around the sun. -
Ejnar Hertzsprung
Ejnar Hertzsprung, born Oct. 8, 1873, died Oct. 21, 1967, Danish astronomer who classified types of stars by relating their color to their absolute brightness—an accomplishment of fundamental importance to modern astronomy. -
Yuri Gagarin
Yuri Gagarin was born March 9, 1934, and died March 27, 1968, and was a Soviet pilot and cosmonaut. He became the first human to journey into outer space when his Vostok spacecraft completed one orbit of the Earth on 12 April 1961. -
The Apollo Program
The Apollo program, was the third United States human spaceflight program carried out by the National Aeronautics and Space Administration, which succeeded in landing the first humans on the Moon from 1969 to 1972 -
First Space Shuttle Flight
The Space Shuttle program was the fourth human spaceflight program carried out by the National Aeronautics and Space Administration, which accomplished routine transportation for Earth-to-orbit crew and cargo from 1981 to 2011. -
Mars Pathfinder Expedition
It was a relatively inexpensive mission that tested out many of the technologies build into later missions, like the Mars Exploration rovers Spirit and Opportunity. The purpose of Pathfinder was to prove that the concept of “faster, better and cheaper” missions would work. -
Cassini Orbiter
The Cassini commonly called Cassini, was a collaboration between NASA, the European Space Agency, and the Italian Space Agency to send a probe to study the planet Saturn and its system, including its rings and natural satellites. -
Neil Armstrong
Neil Armstrong was born August 5, 1930, and died August 25, 2012, and Neil Armstrong was an American astronaut and aeronautical engineer who was the first person to walk on the Moon. He was also a naval aviator, test pilot, and university professor. -
John Glenn
John Glenn was born July 18, 1921, and died December 8, 2016, and he was one of the Mercury Seven, military test pilots selected in 1959 by NASA as the nation's first astronauts. On February 20, 1962, Glenn flew the Friendship 7 mission, becoming the first American to orbit the Earth, and the fifth person and third American in space. -
Difference between refracting and reflecting telescopes
A reflector telescope uses two mirrors instead of two lenses. Isaac Newton developed this telescope to combat chromatic aberration. Light from an object enters the telescope tube and is reflected off a curved mirror at the end of the tube. -
Find a current astronomy event
The Hubble Telescope is back in action because the camera was fixed and is ready to go.
