Download Lunar Phases, Eclipses, and Ancient Astronomy: A Study of Lecture Notes - Prof. Grace Demi and more Study notes Astronomy in PDF only on Docsity! Keep up with the READING. Study handouts and review your notes. Reminders: Astrology Expt. due in discussion Sept. 20 or 21 Requires 4 days! See pages 9 & 10 of syllabus for details. LECTURE SUMMARY (9/13 & 9/15) A green handout on lunar phases and eclipses was distributed in lecture. Keep in mind that how the Moon appears to us on Earth depends on the position of the Sun (source of light) and the position of the Moon. On the handout you should fill in the appearance of the Moon (we did some of this in class). Using the green lunar phases handout, we completed times of moonrise and moonset. Think about the scale model of the Earth-Moon system constructed in class in order to appreciate the tremendous separations between the Sun, Earth and Moon and realize how tiny and skinny the shadows would be that are cast by the Earth and Moon. How solar eclipses would be viewed from Earth was discussed in terms of the umbra and penumbra. A demonstration was done to show refraction. Alignments of buildings and solstices and/or equinox marker monuments demonstrate that ancient people knew some astronomy. Archeoastronomers try to reconstruct the astronomy of ancient civilizations based on alignments and when possible written records. Early civilizations demonstrated an understanding of seasons and constructed calendars using solstices/equinoxes, star positions, or the lunar cycle. The raising of stone markers (like Stonehenge) demonstrates these abilities. Pyramids in Egypt and the Americas are oriented precisely to locations in the heavens. The ability to predict eclipses appeared independently in the eastern (China [2700 years ago], (Babylon, Greece and India about 100 yrs later) and western hemispheres (Mayas [1500 years ago]). A blue handout summarized the findings Greek science flourished in the Mediterranean region from 600 BC to 300 AD. It is during this time that the scientific method using observation/experimentation and an understanding of the world in terms of physical laws is documented. The geocentric theory was formally proposed by Aristotle in 350 BC, refined by Ptolemy in 140 AD and adopted by the Catholic Church in the 13 c. In this model the Earth sits at the center of the universe and the planets, Sun, Moon and stars move in circular orbits. Actually to explain retrograde motion accurately, a complex system of epicycles is necessary for describing planetary motion. The theory was believable due to accuracy in prediction of planetary positions (within 2 degrees per century) and the inability of people to detect stellar parallax. The last Greek astronomer mentioned in class was Hipparchus. His discovery of precession and its effects has affected the placement stars near the celestial poles and the positioning of the equinoxes. These ideas will be further explored during the astrology experiment group discussion in discussion section Sept. 20 & 21. The revival of the heliocentric theory begins with Copernicus. Since he used circular orbits in his sun-centered model, predictions of planetary positions were no more accurate than with geocentric theory. He could only argue his model was simpler, but had to assume that the stars were too far away to show parallax. A comparison chart was given to highlight differences between geocentric and heliocentric theories.
