History of Astronomy

Aristotle

322 BCE

(384 BC - 322 BC) Proved earth was spherical and it was in the center of the universe.

Hipparchus

120 BCE

( 190 BC - 120 BC) Founder of trigonometry. Most famous for incidental discovery of precession of the equinoxes. Created the year and calculated the distance between the earth and the moon. Also calculated the stars.

Ptolemy

170

(100 AD- 170 AD) Ptolemy’s model - Mathematical model of the universe- thought all celestial objects orbited the universe. Said earth was geocentric. Geocentric- earth centered.

Copernicus

1543

(1473- 1543) Heliocentric model- system in which the planets revolve around the earth, and, together with it, around the sun. Heliocentric- the sun is at the center. He also found out how the universe works with the scientific method.

Tycho Brahe

1601

(1546-1601) Was one of the first helpers that helped prove the sun was in the center with overturning the belief in favor of a heliocentric model. Known for precise instruments that helped him to make his accurate observations. He recorded enough data on the motion of the Sun, planets, and moon relative to the fixed stars and planets to within 1 arc minute.

Refracting Telescope

1608

(1608) An optical telescope that has lens to form an image. It is different than the reflecting because it uses one or more curved mirrors that reflect light and form an image.

Hans Lippershey

1619

(1570- 1619) He was the first person to try to obtain a potent of the telescope and associate with it. Made the telescope and sometimes also credited for the compound microscope. The telescope has 3x magnification.

Johannes Kepler

1630

(1571- 1630) Worked with Tycho Brahe. Discovered planets orbit elliptically (Oval). He also discovered the laws of planetary motion. Unification of astronomy and physics.

Galileo

1642

( 1564-1642) From Italy. Discovered the first four main moons of Jupiter: Io, Europa, Ganymede, and Calisto. He founded the telescope and the scientific method. Found the rings of Saturn the stars not being attached to some shell and found sun spots.

Reflecting Telescope

1668

(1668) One or more curved mirrors that reflect light and form an image. The first one was made my Sir Isaac Newton. It is different than the refracting telescope because the refracting telescope is an optical telescope that has lens to form an image.

Giovanni Cassini

1712

(1625-1712) 1st person to observe the division in the rings of Saturn. He is also known for 4 of Saturn’s moons, the Cassini Division, Cassini’s laws and Cassini oval.

Sir Issac Newton

1727

( 1642- 1727) He created calculus and formulated the law of gravitation. Newton also discovered the laws of motion. He was the first person to explain tides significantly and invented the reflecting telescope in 1668.

William Herschel

1822

(1738-1822) Founded sidereal astronomy for the systematic observation of the heavens. Discovered the planet Uranus and its moons. He also discovered more of Saturn’s moons. Herschel performed a simple experiment determining temperature of the different colors of sunlight passed through a prism.He found that color comes in different temperatures

Percival Lowell

1916

(1855-1916) He fueled speculation that there were canals on Mars. He also discovered asteroids and the planet Pluto. He did his studies in Flagstaff, AZ. This is where he built an observatory and studied Mars.

Karl Janksy

1950

(1905-1950) Discovered radio waves emanating from the Milky Way. Radio waves are the longest type of energy waves.

Edwin Hubble

1953

(1889-1953) Using the color of the stars, discovered the universe is expanding. Hubble’s Law, galaxies are moving away from each other. He observed cosmology and is said to be one of the most important astronomers of all time.

Albert Einstein

1955

(1879-1955) Developed the theory of relativity and which is one of the two killers in modern physics. His work helped for its influence on the philosophy of science.

Sputnik

1957

(1957) The world’s first artificial satellite. It took about 98 minutes to orbit the earth on its elliptical path. The importance of sputnik to the U.S. In the midst of the Cold War, Russia was successful in launching the first satellite into space to orbit Earth.

Yuri Gagarin

1961

First human (Soviet) to orbit Earth 108 minutes. (1961)

Ejnar Hertzsprung

1967

(1873-1967) He developed the HR diagram with Henry Norris Russell. HR diagram shows the correlation and brightness of the stars.

Apollo Missions

1972

(1961-1972) The third United States human spaceflight program out by the National Aeronautics and Space Administration. Program is to bring astronauts to space and bring them back to Earth safely.

First Space Shuttle Flight

1981

(1981) Space Shuttle Columbia. Launched straight up like a rocket and lands like an airplane. Attached to a rocket.

Mars Pathfinder Expedition

1997

Launched in 1996 and landed in 1997. It took 1 year to get to Mars.

SpaceX Falcon Heavy

2012

Made by SpaceX. Falcon Heavy is a heavy-lift launch that is partially reusable. This is derived by the Falcon 9. It had four flights. The first flight was in 2010, the second was also in 2010, the third was in 2012 along with the fourth one.

Neil Armstrong

2012

(1930-2012) First person to step on the moon in 1969. Apollo 11 was the spaceflight that landed two humans on the moon. Neil Armstrong and pilot Buzz Aldrin, both American, landed the lunar module Eagle on July 20, 1969.

John Glenn

2016

(1921- 2016) Became the first American to orbit the Earth circling it 3x in 1962.

Cassini Orbiter

2017

Mission started 1997 and ended in 2017. It was called Cassini because it was a collaboration between NASA and the Italian Space Agency. This was to send a probe to study Saturn and its system. This means including its rings and natural satellites.