
An algebrabased overview of elementary and (mostly) pretelescope astronomy, for personal study, also for middle school (some), high school (mostly) and beginning college. Starting with the apparent motions of the Sun and stars on the celestial sphere, it explains the seasons of the year, latitude and longitude, time zones and universal time, and the basics of navigation. Next calendars are describedJulian and Gregorian, Metonic (esp. Jewish), Moslem, Persian and even Maya. After that the site tells how the spherical shape of the Earth was recognized and measured, leading to the formula for the distance of the horizon, the concept of parallax and the ways the ancient Greeks estimated the distance of the Moon. The Greeks also tried to derive the distance of the Sun, starting the road to heliocentric theory, with roles by Ptolemy, Copernicus, Galileo and Kepler. The section ends with a fairly detailed discussion of Kepler's laws and planetary orbits, which serves as a bridge to the next section, on Newtonian Mechanics. Interspersed with the above are three web pages on the Moon (which may also be tied to the Greek calculations of the Moon's distance) and one on the precession of the equinoxes, connected to the Milankovitch theory of ice ages.
1a. The Celestial Sphere 1b. Finding the Pole Star 2. The Path of the Sun, the Ecliptic 2a. Building a Sundial 3. Seasons of the Year 3a. The Angle of the Sun's Rays 4. The Moon: the Distant View 4a. The Moon: A Closer Look 4b. Optional: Libration of the Moon 5. Latitude and Longitude 5a. Navigation 5b. The CrossStaff 5c. Coordinates 6. The Calendar 6a. The Jewish Calendar (optional) 7. Precession 8. The Round Earth and Christopher Columbus 8a. Distance to the Horizon 8b. Parallax 8c. How Distant is the Moon?1 8d. How Distant is the Moon?2 The central role of the Sun 9a. Aristarchus: Is Earth Revolving around the Sun? . 9a1. The Earth's Shadow 9b. The Planets 
P1 Links and Tables about the sections below. P2 Mercury P3 Venus P4 Earth P5 Mars P6 Asteroids P7 Jupiter P8 Io and other Jupiter moons P9 Saturn P10 Telescopes P11 Uranus P12 Neptune P13 Pluto and the Kuiper belt P14 Comets and other small objects 9c. Copernicus, Galileo, and the Discovery of the Solar System
Guide to the sections on Kepler's Laws which follow below.
10. Kepler and his Laws
Optional: The 2004 Transit of Venus 
Author and Curator: Dr. David P. Stern
Mail to Dr.Stern:
stargaze["at" symbol]phy6.org
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Last updated: 9222004
Curators: Robert Candey, Alex Young, Tamara Kovalick
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