An algebra-based overview of elementary and (mostly) pre-telescope 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 described--Julian 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
5b. The Cross-Staff
6. The Calendar
6a. The Jewish Calendar (optional)
8. The Round Earth and Christopher Columbus
8a. Distance to the Horizon
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?
. 9a-1. The Earth's Shadow
9b. The Planets
P-1 Links and Tables about the sections below.
P-8 Io and other Jupiter moons
P-13 Pluto and the Kuiper belt
P-14 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
Author and Curator: Dr. David P. Stern
Mail to Dr.Stern: stargaze["at" symbol]phy6.org .
Last updated: 9-22-2004