Discoveries/Events of Astronomy



384 BCE - 322 BCE

Aristotle believed that the Earth was round. He used many proofs, such as observing the shadow on the moon during lunar eclipse that always made a circle. He used these proofs to prove to people that the Earth was not flat, but round.


276 BCE - 195 BCE

Eratosthenes is a Mathematician, Astronomer, and a Geologist. He calculated the Earth's circumference from the difference in shadow length of two sticks that were placed by a known distant apart.

Claudius Ptolemy

90 AD - 168 AD

He created a model where the sun, stars, planets, and moons revolved around the Earth. The Earth was in the center of the solar system.


476 CE - 550 CE

He was the first Indian Astronomer and Mathematician who was able to predict solar and lunar eclipse by using plane trigonometry to spherical geometry. By using trigonometry and geometry, he was also able to give a statement about westward motion of the stars. He figured that it was due to the spherical Earth's rotation on its axis. He also correctly described the luminosity oh the moon and planets to reflected sunlight.

Abd-al Rahman al-Sufi (Azophi)

903 CE - 986 CE

He made the first observation of a group of stars outside of the Milky Way. It's called the Andromeda galaxy. He discribed the nebulosity of the nebula in the Andromeda galaxy.

Nicolaus Copernicus

1473 - 1543

He proposed a model of the solar system that involves the Earth revolving around the sun and the sun being in the center.

Galileo Galilei

1564 - 1642

He used the telescope to prove that the heliocentric model was correct. He was in prison for defending the idea of the Earth revolving around the sun. He also discovered the first four moons of Jupiter by using the telescope.

Jonannes Kepler

1571 - 1630

He was determined that the Earth revolves around the sun not in circles but in ellipses. So, he calculated 3 laws involving the moons of planets that astronomers today still use.

Giovanni Cassini

1625 - 1712

A Italian Astronomer that measured how long it took for planets Jupiter and Mars to rotate. He also discovered the 4 moons of Saturn and the gap of the planet's rings.

Christiaan Huygens

1629 - 1695

He proposed the first theory of the nature of light. He improved the telescope and it allowed him to make the first observation of Saturn's rings and then he discovered its moon called Titan.

Sir Isaac Newton

1642 - 1727

A English Astronomer that calculated 3 laws describing motions of forces between objects. He is famous for his work on forces and till today we still use his laws.

Edmond Halley

Approx. 1656 - 1742

He's a British scientist that proposed that the comets in 1456, 1531, 1607, and 1682 were all the same and that another will be coming in 1758. The comet was named after him.

Charles Messier

1730 - 1817

He composed a database of nebulae. It included 103 objects and other objects included. He also discovered 13 comets in his lifetime.

William Herschel

1738 - 1822

He discovered Uranus and its 2 brightest moons. He also discovered 2 of Saturn's moons and the Martian ice caps. He also trained his sister, Caroline Herschel in Astronomy.

Caroline Herschel

1750 - 1848

She became the first woman to discover a comet and identifying several comets over the courses of her lifetime.

Henrietta Swann Leavitt

1868 - 1921

Henrietta discovered the brightness of a special flashing star known as a cepheid variable that was related to how often it plused. This allowed astronomers to calculate the distance of stars and galaxies, the Milky Way, and the expanding universe.

Albert Einstein

1879 - 1955

Einstein discovered a new way of looking at the universe. He said that the law of physics were the same throughout the universe and that the speed of light in a vaccuum is constant. He also said that space and time linked in a time and space, which is distorted by gravity.

Harlow Shapley

11/2/1885 - 10/20/1972

He used RR Lyrae stars to estimate the Milky Way and parallax for the sun. He was able to correctly estimate the size of the Milky Way and the general location of it's center.

Edwin Hubble

1899 - 1953

He calculated that there was other galaxies outside of the Milky Way. By looking at the sky every night, he determined that the universe itself is expanding which later he made calculations and became known as Hubble's law.

Frank Drake

1930 - Present

He was one of the first person to search for alien life. He's also participating in a ongoing search for optical signals of intelligence orgin. He's also interested in numerous red dwarf stars which is much less bright than the sun.

Amo Allan Penzias

4/26/1933 - Present

He used ultra-sensitive cryogenic microwave receivers to discover cosmic microwave background radiation.

Carl Sagan

1934 - 1996

He is a famous Astronomer that teaches people around the world about Astronomy as he brakes down complicated subject that are hard to understand and make it interesting. He also mangaged to popularize Astronomy than any other individual.

William K. Hartmann

1939 - Present

William proposed the most widely accepted theory on the formation of the moon in 1975. After a collision with a large body scooped, debris from the Earth coalesced into the moon.

Stephen Hawking

1942 - Present

The proposed that the universe has a beginning and is likely to have an ending. He also suggestes that there is no borders or boundaries

Jocelyn Bell Burnell

07/15/1943 - Present

She discovered a pulsar, short for pulsating radio star. She was suppose to use radio telescope that would track quasars but then the markings were too fast and regular that it couldn't be a quasar.

3 questions


Who calculated the size of the Milky Way?
A. No one B. Caroline Herschel C. Harlow Shapley D. Albert Einstein

3 Questions


Who was the one who discovered that the Earth was round?
A. Eratosthenes B. Aristotle C. Stephen Hawking D. Azophi

3 Questions


Who made the laws of the motion of forces?
A. Isaac Newton B. William Herschel C. Edwin Hubble D. Neil DeGrasse Tyson