Ancient Astronomers

Eratosthenes

240 BCE

-Made the 1st good measurement of Earth's size (circumference)
-Discovery made: 240 BC
-Significance: He knew the Earth was round, but this proved and solidified his claim.

Claudius Ptolemy

127

-Discovered evection/lunar theory- irregularity in the moon's motion
-Discovery made: Sometime between 127-141 AD
-Significance: Explains that the moon goes all the way around the Earth in the same time it takes to spin around just once

Nicolaus Copernicus

1543

-Came up with the Heliocentric System (The idea that planets orbit around the sun)
-Discovery made: 1543
-Significance: It is an important concept (that is true) that says the sun is the center of everything. (All planets orbit around it).

Tycho Brahe

1572

-Discovered the new star Cassiopeia and made publications of it
-Discovery made: 1572
-Significance: The publications were accurate, and showed that this new star is farther away from the moon, and is among the fixed stars.

Johannes Kepler

1600

-Created the 3 Laws of Planetary Motion "(1) the planets move in elliptical orbits with the Sun at one focus; (2) the “area law” (3) the harmonic law.” -Britannica.com
-Discovery made in the early 1600s
-Showed a precise distance between the planets and the sun, and the time it takes for planets to revolve around the sun

Sir Isaac Newton

1664

-Invented Calculus
-Discovery made: Between 1664-1669
-Significance: His invention led to the forming of laws of gravity and motion.

Albert Einstein

1903

-Created E=mc2
-Discovery made: 1903
-Significance: His discovery helped expand Newton's theories later on