1st Hour - History of Astronomy Quiz
After test please complete the virtual laboratory.
2nd Hour - History of Astronomy Quiz
After test please complete the virtual laboratory.
After test please complete the virtual laboratory.
2nd Hour - History of Astronomy Quiz
After test please complete the virtual laboratory.
History of Astronomy Notes:
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Astronomy is the science that studies the universe. It includes the observation and interpretation of celestial bodies and phenomena.
The Beginnings of Astronomy Archaeological records show that astronomy is one of the first natural sciences developed by early civilizations all over the globe. Ancient astronomers could perform only limited investigations of the sky, using rudimentary aids to the human eye. Even so, humankind had already begun the measurement of the positions of celestial bodies, making astrometry – the science of charting the sky – one of the oldest branches of astronomy. Ancient astronomers were able to differentiate between stars and planets, as stars remain relatively fixed over the centuries while planets will move an appreciable amount during a comparatively short time. Early cultures identified celestial objects with gods and spirits. They related these objects to phenomena such as rain, drought, seasons, and tides. It is generally believed that the first astronomers were priests, and that they understood celestial objects and events to be manifestations of the divine, hence early astronomy’s connection to what is now called astrology. The first documented records of systematic astronomical observations date back to the Babylonians around 1000 BCE. From this cradle of civilization in Mesopotamia – in the southern part of present-day Iraq – astronomers had built up knowledge of the celestial bodies and recorded their periodic motions. |
Curiosity alone did not inspire the earliest astronomers: astronomy and astrometry were practical sciences too. Monitoring the motions of stars and planets in the sky was the best tool to track time, which was fundamental for agriculture, religious rituals and navigation. The first documented records of systematic astronomical observations date back to the Babylonians around 1000 BCE. From this cradle of civilization in Mesopotamia – in the southern part of present-day Iraq – astronomers had built up knowledge of the celestial bodies and recorded their periodic motions. But they had no idea how far away the stars and the planets were. Ancient Greece Astronomy flourished at Alexandria, a Greek colony off the northern coast of Egypt, with a renowned library and museum. The dominant view of the cosmos among scientists was geocentric, with the Earth being at the center of the Universe and everything else revolving around it, but there were some who were edging closer to the truth. |
Aristarchus was one of the few supporters of the heliocentric system, identifying that the Earth travelled around the Sun rather than the other way around. A proficient mathematician, he tried to assess the relative distance of the Sun and the Moon from Earth, by measuring the angle between them when the Moon appears exactly as one quarter. With the help of trigonometry, he determined that the Sun is 18 to 20 times more distant from Earth than the Moon. He had the right idea, but the measurement was not very precise; current data show that the Sun is about 400 times more distant than the Moon.
Greek astronomer Hipparchus compiled the first star catalogue. A record of his work was handed down by Ptolemy, an astronomer writing three hundred years later at Alexandria – by then part of the Roman Empire. To measure angles in the sky, Hipparchus employed the ancient Babylonian practice, still in use today. Hipparchus's catalogue, one of the earliest successful attempts to chart the heavens, lists the positions of 850 stars across the sky. Hipparchus also created the magnitude system for describing the brightness of stars, which is still in use today, and studied the relative distance of the Sun and the Moon from Earth. |
Astronomy Grows
While Europe languished in the Dark Ages, astronomy flourished in Asia and in the Islamic world. Extensive observations were performed in the Chinese and Indian empires, including the compilation of stellar catalogues. In the Islamic world, observations of the sky were accompanied by the study and translation of texts from ancient Greek scientists. Islamic scholars built exquisite astronomical instruments to measure angles in the sky. They improved on the quadrant, a measuring device shaped as a quarter of a circle that was originally proposed by Ptolemy, and invented the sextant, a similar instrument. The flow of discoveries and inventions from other cultures and territories catalyzed the revival of science in Renaissance Europe. In astronomy, the rediscovery of Ptolemy's original texts would eventually lead Polish astronomer Nicolaus Copernicus to revolutionize the view of the cosmos, with the shocking revelation that Earth is not the center of the Universe. Copernicus published his theory of a heliocentric system in 1543, identifying the Sun as the center of the Universe, with the Earth and the other planets bound to move around it. Although the heliocentric view described planetary motions in a simpler and more orderly fashion than Ptolemy's geocentric system, it would take at least a century before this controversial model became accepted both within and beyond the scientific community. Even one of astronomy's great minds, Tycho Brahe, rejected heliocentrism. However, from his base in Denmark, Brahe made great strides in observational astronomy. Brahe built the greatest astronomical observatory before the invention of the telescope. With the aid of large quadrants and sextants, he compiled a catalogue with the positions of about 1000 stars. 
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Geocentric vs. Heliocentric Models
The Greek mathematician Eudoxus, born around 400 BC, is considered by many to be the first to have produced a geocentric model of the Universe. Other famous astronomers and thinkers from history argued for the geocentric model, including Plato and Aristotle and the Greco-Roman astronomer Ptolemy. The ancient Greeks, the Romans, the great Islamic astronomers of the 8th-13th centuries… all were firm in their belief that Earth was at the center of the Universe, and everything else revolved around it. Well, almost all. In fact, a heliocentric model of the Solar System – ie, one with the Sun at its center – was first proposed by the Greek scholar Aristarchus. 
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Nicolaus Copernicus was the first astronomer to really champion the idea, publishing his De revolutionibus orbium coelestium (‘On the movement of the heavenly spheres’) in 1543.
However, there was a problem: Copernicus’s calculations and predictions didn’t really stack up, mostly because they assumed the orbits of the planets to be circular, whereas we now know that they are elliptical. Italian astronomer Galileo Galilei provided a number of scientific insights that laid the foundation for future scientists. Galileo was accused of heresy for his support of the Copernican theory that the sun was at the center of the solar system. This was revolutionary at a time when most people believed the Earth was in this central position. In 1616, he was forbidden by the church from teaching or advocating these theories. Galileo’s most important contributions were his descriptions of the behavior of moving objects and improvements made to the telescope. This not only proved that we didn’t live in a geocentric universe (because here were some heavenly bodies that clearly did NOT orbit our own Earth), it also showed that smaller bodies can orbit larger bodies that are themselves in motion. |
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Heavenly Motion
Johannes Kepler was a German mathematician and astronomer who discovered that the Earth and planets travel about the sun in elliptical orbits. Kepler discovered three laws of planetary motion:
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His work laid the foundation for Isaac Newton's theory of universal gravitation. English scientist - Sir Isaac Newton (1642—1727) explained gravity as the force that holds planets in orbit around the Sun. Although others had theorized the existence of gravitational force, Newton was the first to formulate and test the law of universal gravitation. The universal law of gravitation, helped explain the motions of planets in the solar system and how our Sun is pulled towards the center of the Milky Way Galaxy. Isaac Newton changed the way we understand the Universe. Revered in his own lifetime, he discovered the laws of gravity and motion and invented calculus. He helped to shape our rational world view.
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Timeline Project
Create a timeline of the important historic events in the history of astronomical and scientific discoveries through the 1700s. There should be at least 10-15 important points on your timeline including brief statements of each event.
o Add pictures for more credit
o Make sure your save your work and email it to yourself
Online Timeline Application:
Timeline Project
o Add pictures for more credit
o Make sure your save your work and email it to yourself
Online Timeline Application:
Timeline Project
