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Saturn from Cassini Astronomy 161:
An Introduction to Solar System Astronomy
Prof. Richard Pogge, MTWThF 2:30

Lecture 1: An Introduction to Astronomy

"The most incomprehensible thing about the Universe is that it is comprehensible."
Albert Einstein
"It will seem difficult at first, but everything is difficult at first."
Miyamoto Musashi, The Book of Five Rings (Gorin no sho)

What is Astronomy?

Astronomy is derived from the Greek astronomos:
astron = star
nomos = a system of laws

Today "Astronomy" is synonymous with "Astrophysics", the study of the physics of celestial objects; the solar system and its consituents, the properties, birth, life and death of stars, interstellar gas and dust, galaxies and clusters of galaxies, and finally the study of the Universe as a whole ("Cosmology").

In this course we will be studying the historical development of modern astronomy, starting with our discovery of the nature of our Solar System.

What is Science?

Astronomy is one of the oldest of the sciences. There are many ways to define science in general, but a way I have found useful is as follows:

Science is not so much about what we know, but about how we have learned to confront what we do not know.
In general, We will be seeing illustrations of all of these aspects of science in our study of astronomy.

Three Questions of Astronomy:

Astronomy as practiced often comes down to addressing three broad questions about a phenomenon, in this order:

1) What is it?

Describe it: how bright is it, how far away, what is it made of, ...

2) How does it work?

Underlying physics (testable theories).

3) How does it evolve?

How did it form, how will it develop over time?

The main topics covered in Astronomy 161

We will be covering 4 related topics in this course:

Descriptive Astronomy

Apparent Motions of the Sun, Moon, & Stars
The Seasons
Timekeeping & Calendars
The Phases of the Moon
Eclipses of the Sun and Moon
Motions of the Planets
The Historical Origins of Astronomy

Ancient Astronomy & the Ptolemaic System
The Copernican Revolution:
The Newtonian Synthesis
The Physics of Astronomy: Gravitation, Matter & Light

Newtonian Gravity
Nature of Matter
Nature of Light
The Tools of the Astronomer
The Solar System

The Earth & The Moon
The Sun
Comparative Planetology
The Origin of the Solar System
Worlds beyond the Solar System

Main Themes of this Course

There are three main themes that tie together all of the material we will cover in Astronomy 161:

Return to [ Unit 1 Index | Astronomy 161 Main Page ]
Updated: 2007 September 16
Copyright Richard W. Pogge, All Rights Reserved.