History of Astronomy

Aristotle

322 BCE

Aristotle had proof that the earth was round and believed it was the center of the universe. He build a geocentric model of the earth. He said that the Sun, planets, and stars were spheres that revolved around the Earth.

Ptolemy

168

Using Hipparchus’ observations Ptolemy created a model that predicted the movements of the Sun, Moon, planets, and stars. The model was called the Ptolemaic system, which showed the earth as the center of the universe and that all objects move at a constant speed in a circular orbit.

Copernicus

1543

Copernicus proved the earth is not the center of the universe and the sun was. He believed the Ptolemaic system was unrealistic and made some corrections keeping the orbit circular. The idea was not popular but other astronomers like Brahe and Galileo helped him prove his theory.

Tycho Brahe

1601

Tycho Brahe built an observatory and studied the positions of the stars for over twenty years. He believed that the universe was a blend of the Ptolemaic and Copernican models. In result of that he built his own model where the planets orbit the sun and the sun orbits the earth.

Hans Lippershey

1619

Hans Lippershey a Dutch inventor created the telescope. No one knows how he had come up with the idea but there are many roomers. The exact design of the of the first telescope is also unknown but it is considered to have two convex lenses which when looking through both makes an image appear larger.

Johannes Kepler

1630

Johannes Kepler Tycho Brahe’s assistant and student used his records to develop three laws of planetary motion. He supported the Copernican model but had trouble fitting in Tycho Brahe’s observations of Mars into the model with circular orbit. He decided to use elliptical orbit or a rectangular oval shaped orbit to describe the motions of the planets this was his first law. His second law was that a line from the Sun to a planet sweeps out equal areas in equal amounts of time.

Galileo

1642

Galileo discovered many things for example he was the first to notice craters on the moon. He also tracked the phases of Venus and made many improvements to the telescope. Galileo also is very famous for discovering four of Jupiter's moons, Io, Ganymede, Europa and Callisto. Throughout his work he came to a conclusion that all things revolve around the earth.

Giovanni Cassini

1712

Giovanni Cassini an Italian astronomer was the first to discover the separation of Saturn's rings. His discovery is now called the Cassini division. He also found four moons orbiting Saturn and measured the periods of rotation of Mars and Jupiter.

Sir Isaac Newton

1724

Sir Isaac Newton was a mathematician who explained the models of Copernicus and Kepler in words of mathematics. Newton is most famous for his Theory of Universal Gravitation also known as gravity. He used gravity as the structure of Kepler’s laws of planetary motion later figuring out that the governing of planets had the same laws that were governing motion on the surface.

Difference between refracting and reflecting telescopes

1724

Refractor Telescopes:The lens at end of the telescope(end without eye piece) takes in the light of the object being looked at and focuses on it. The lens on the side with an eyepiece enlarges what the other lens focused on.
Reflector Telescopes:Made by Isaac Newton in 1724 with mirrors instead of lenses. Light from the object goes into the end of the telescope and is reflected off a curved mirror. It like this so the object being observed doesn't show a rainbow around what you are looking at.

William Herschel

1822

William Herschel discovered Uranus and two of its moons. He also discovered two of Saturn's moons and multiple asteroids. Herschel also discovered the ice caps on Mars. Over his lifespan he made a catalog of 2,500 astronomical objects.

Percival Lowell

1916

Percival Lowell researched life on mars and also began the research on discovering Pluto. He also was the founder of the Lowell Observatory.

Karl Jansky

1950

Karl Jansky began the science of radio astronomy. He discovered radio waves coming from space.

Edwin Hubble

1953

Edwin Hubble discovered galaxies moving away from ours. His theory is called Hubble’s Law and it supports the big bang theory

Albert Einstein

1955

Albert Einstein figured out the equivalence between mass and energy(E=mc^2). Einstein published multiple theories of relativity. He figured out how the speed of light effects time and space (special relativity) and a more accurate theory of gravity.

Sputnik

Oct 4, 1957

It was a satellite launched by the Soviet Union on October 4, 1957. Sputnik only lasted three weeks then eventually plummeted back to earth. This was the beginning of the cold wars. There ended up being 5 missions launched by the Soviet Union

Yuri Gagarin

Apr 12, 1961

Yuri Gagarin was a soviet pilot. He was the first human to take a trip to outer space when his ship made one orbit around earth.

John Glenn

1962

John Glenn was the first American to orbit the earth. In 1962 he went on the famous trip where he orbited the earth 3 times.

Ejnar Hertzsprung

1967

Ejnar Hertzsprung figured out the distance between our galaxy and another called the Small Magellanic Cloud. He was also one of the inventors who invented the Hertzsprung-Russell diagram which shows the relationship between the absolute magnitude and the e spectral type of stars also known as dwarf stars.

Neil Armstrong

1969

Neil Armstrong was an american astronaut and engineer. He is famous for being the first man to walk on the moon. He said a quote on the moon and it is now very famous: That's one small step for a man, one giant leap for mankind.

The Apollo Program

1972

There were 17 Apollo missions and they were what got Neil Armstrong onto the moon. Only six of the missions made it to the moon and some orbited. Sadly some of the missions didn't go as well and lives were lost.

First Space Shuttle flight

Apr 12, 1981

This was the first mission of the space transport system April 12, 1981. The space craft was reusable and could take people and cargo up in it.

Mars Pathfinder Expedition

1996

The Mars Pathfinder Expedition launched 1996 delivered a robot to mars. The shuttle returned with more information than expected. Both the lander and rover were equip with all the new data tracking technologies.

Cassini orbiter

1997

The Cassini orbiter made a seven year trip in a ship to Saturn. Cassini made it to Saturn in 2004 and finished research which included info about its moons and rings in 2008. It returned to earth in 2015 with all the data.

Stephen Hawking

2018

Stephen Hawking believed the universe has no boundary meaning you could go forward forever not running into a wall or "the end". He studied the laws of the universe. Hawking demonstrated Einstein's theory of relativity suggesting space and time started when the universe was created and ends at black holes. Sadly Stephen Hawking died march 2018.