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Astronomy 161
An Introduction to Solar System Astronomy
Prof. Scott Gaudi

Lecture 1: Introduction to Astronomy

An Exciting Time

Solar System Astronomy (Planetary Science) is in the midst of a real Renaissance
Major discoveries in the last few years include:
A new population of small bodies beyond Neptune.
New dwarf planets in the outer solar system.
New moons of Pluto.
Dozens of new moons of the giant plantes.
Also the demotion of Pluto!

What is Astronomy?

From the Greek astronomos
astron = star
nomos = a system of laws

Today Astronomy means Astrophysics - the study of the physics of celestial objects

What is Science?

Science is not just a collection of facts, but a process of critical thinking that leads to understanding the world around us.

Starts with a collection of careful observations of the world around us
Provides a framework to understand these observations
This framework can then predict future observations and deepen our understanding

The Scientific Method

1. Gather Facts
2. Create a Hypothesis to Explain these Facts
3. Create a Prediction from the Hypothesis
4. Test this Prediction against other Facts

Successful? Create new predictions and gather more facts Unsuccessful? Return to Step 2

Law, Hypothesis, and Theory

Scientific Law: statement of fact meant to concisely describe observations
Newton's Law of Gravity: objects are attracted to one another because they have mass
Scientific Hypothesis: educated guess at an explanation of observation
Apple Hypothesis: Apples fall toward the Earth, therefore apples and the Earth have mass
Scientific Theory: explanation of a large set of observations that merges many hypothesis in a simple way
Einstein's General Theory of Relativity: mass curves spacetime and causes objects to attract one another

Examples: Theory of Relativity, Quantum Theory

Descriptive Astronomy

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

Historical Origins of Astronomy

Classical Astronomy
Copernican Revolution
Newtonian Synthesis

Physics of Astronomy

Newton's Laws
Orbits and Tides
Light and Atoms
Electromagnetic Spectrum
Atomic Structure
Interaction of Light and Matter
Tools of the Astronomer

The Solar System

The Earth and Moon
Comparative Planetology
Terrestrial Planets
Jovian Planets
Comets, Asteroids, and the Outer Solar System
Origin of the Solar System
Other Solar Systems
Life in the Universe

See A Note about Graphics to learn why some of the graphics shown in the lectures are not reproduced with these notes.

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