A Practical Guide to Astronomy
The Early Astronomers
From early man until today, we have been staring at the same stars, wondering about the heavens above. The ancients studied the moon & sun to learn when to sow their crops and when to harvest. We still use this method to this day.
15,000 BC - Ice Age people start to track the number of moons by scratching marks into bones.
1200-1000 BC- Babylonians study 'astrology' - the belief that people's lives were influenced by the stars. They invented the 12 signs that are still used today. Around the same time, the Greeks name most of the stars and the constellations (Hercules, Perseus, Cassiopea and Cygnus). They also name the "the wandering stars." We now know these wandering stars as planets. The Greeks named these after their gods, Mercury, Venus, Mars & Jupiter.
332 BC- Alexander the Great builds a great museum-library-observatory at the mouth of the Nile in Alexandra.
280 BC- Aristarchus (Greek) stated that the Sun was the center of the 'solar system'. It was almost 1800 yrs later that his theory would be widely accepted.
240 BC- Eratosthenes figured out the size of the Earth.
Year O - At the time of Christ, Egyptians & Chinese were also heavily into the study of the stars.
120 AD- Egyptian astronomer Ptolemy (a.d. 90-168) is credited with the creation of the elaborate mechanism by which he (and later astronomers) calculated the movements of the stars and planets and the moon around the earth.
Ptolemy's most important work was completed early in his career, Almagest. Written originally in Greek, this work on astronomy was translated into Arabic in the ninth century, and in 1410 it was translated into Latin. While never completely unknown, its reappearance during the Renaissance buttressed Catholic doctrine on the centrality of human creation.
1054- Oriental astronomers recorded a breif flaring star, now known as a supernova.
1200 AD- the mariner's compass with a magnetic needle comes into use.
1510 AD - Nicolaus Copernicus (1473-1543) Polish astronomer & mathemetician posumously publishs his theories that opposes common Christian beliefs of the time. The book stated that the sun was the center of our solar system. His book was banned by the Roman Catholic Church until 1835.
1618- Johannes Kepler stated that the Earth moved around the Sun in an ellipse ( a squashed circle.)
1905- Albert Einstein published his Theory of Relativity. This led to the famous E=MC squared (energy is equal to mass times the speed of light squared). This formula helped us understand the atom and the fact that gravity can bend light.
1924- Edwin Hubble (1889-1953) discovered that our Milky Way was not the center of the universe, but rather only one galaxy in among billions. He calulates the distance to the Andromeda and Triangulum 'nebulas'. He also measures the redshift of the spectra of the galaxies and states that the universe is expanding.
1967- A Pulsar (a form of radiation) is discovered at Mullard Radio Astronomy Observatory at University of Cambridge.