Big Bang (13.7 billion BC)

The big bang is the leading theory of how our universe became what it is today. This theory talks about our universe starting with a small singularity, then inflating over the next 13.7 billion years to what we see today.

Stonehenge

3100 BC - 2500 BC

Stonehenge is a prehistoric monument that took Neolithic builders an estimated 1,500 years to erect. Located in southern England, it is comprised of roughly 100 massive upright stones placed in a circular layout. Scientists today have yet to understand the importance of this monument to the civilization in that time period. Although, we know at one time it was used as a burial ground.

Aristotle 384 -  BC 322 BC

Was the astronomer that started

the geometric model which stated

the Earth was the center of the universe.

Discovered the planets moved “backwards”

in the sky and named this erratic movement

Retrograde motion.

Eratosthenes 276 - 194 BC

Eratosthenes is also known for

his achievement in . Several

astronomers and mathematicians

before and after Eratosthenes

tried to accurately measure the circumference of the

Earth, but is was Eratosthenes that came through. He found the circumference of the

Earth to be nearly 250,000 stadia (25,000 miles).

Aristarchus 310- 230 BC

Aristarchus was the first astronomer

to suggest that we had a sun based

solar system and was also able to

measure the distance of the sun.

Hipparchus 190 BC - 120 BC

Greek astronomer, geographer, and

mathematician. He is considered the

founder of trigonometry but is most

famous for his incidental discovery

of precession of the equinoxes.

First to discover the Earth’s “wobbled” called precession, it takes 26000 years for one complete wobble.

Ptolemy 90 AD - 168 AD

mathematical theory of the

motions of the Sun, Moon,

and planets. Ptolemy

made his most original

contribution by presenting

details for the motions of

each of the planets.

Nicholas Copernicus 1479 - 1543

In the early 1500s, when virtually

everyone believed Earth was the center

of the universe, Polish scientist

Nicolaus Copernicus proposed that

 the planets instead revolved around the sun.

Tycho Brahe 1546 - 1601

Tycho Brahe was a Danish nobleman

and astronomer, and he was one of the

individuals whose work helped overturn that belief in favor of a heliocentric model of the universe, with the Sun at the center.

Brahe personally believed that the Earth was motionless and at the center of our universe.

Galileo Galilei 1564- 1642

Italian natural philosopher, astronomer,

and mathematician who made contributions

to the sciences of motion, astronomy, and

to the development of the scientific method. His formulation of inertia, the law of falling bodies, and parabolic trajectories marked the beginning of change in the study of motion.

Johannes Kepler 1571 - 1630

Johannes Kepler is one of the most highly r

egarded individuals in astronomy and astrology.

He wrote a number of books detailing various

aspects of space and the objects that exist in it.

Kepler discovered Planetary motion which accurately explained how planets move within their own axis and orbits. Kepler invented an improved version of the refracting telescope, which is also known as the dioptric telescope.