Astronomy 161 - Introduction to Solar System Astronomy

Lecture 20: Tides

Why are there two high tides a day? This lecture examines another of the consequences of gravity, the twice-daily tides raised on the Earth by the Moon. Tides are a conse

Lecture 19: Orbits

Why do Kepler's Laws work? This lecture discusses how Newton applied his Three Laws of Motion and the Law of Universal Gravitation to the problem of orbits. Newton genera

Lecture 18: The Apple and the Moon - Newtonian Gravity

What is Gravity? This lecture reviews the law of falling bodies first described by Galileo, and then Newton's explanation in terms of his Law of Universal Gravitation. Gr

Lecture 17: On the Shoulders of Giants: Isaac Newton and the Laws of Motion

The work of Copernicus, Kepler, and Galileo all contributed to a new way of looking at the motions in the heavens, but did not explain why they move that way. Enter Isaac

Lecture 16: Galileo and the Telescope

Tycho did as much as could be done with the naked eye, a new technology was required to extend our vision, the telescope. This lecture introduces Galileo Galilei, the con

Lecture 15: The Watershed: Tycho and Kepler

In the generation following Copernicus, the question of planetary motions was picked up by two remarkable astronomers: Tycho Brahe, the brilliant Danish astronomer whose

Lecture 14: The Revolutions of Nicolaus Copernicus

In 1543, Nicolaus Copernicus re-introduced the Heliocentric idea of Aristarchus of Samos in an attempt to purge Ptolemy's geocentric system of the un-Aristotelian idea of

Lecture 13: Greek Astronomy

What are the origins of the Geocentric and Heliocentric models put foward to explain planetary motion? This lecture begins a new unit that will chart the rise of our mode

Lecture 12: The Wanderers - Planetary Motions

How do the planets move across the sky? This lecture will review planetary motions, specifically the apparent motions of the five classical planets (Mercury, Venus, Mars,

Lecture 11: The Calendar

Why are there leap years? This lecture explores the astronomical origins of the calendar. We will discuss lunar and solar calendars and their hybrids in history and tradi

Lecture 10: Telling Time

What time is it? This lecture is the first part of a two-part exploration of the astronomical origins of our time-keeping and calendar conventions. Today we will discuss

Lecture 9: Eclipses of the Sun and Moon

Eclipses of the Sun and Moon are among the most glorious spectacles in the sky. This lectures looks at the causes and types of eclipses, and how often they occur. Recorde

Lecture 8: Phases of the Moon

How does the Moon appear to move through the night sky? This lecture introduces the Moon, and describes the monthly cycle of phases. Topics include synchronous rotation,

Lecture 7: The Four Seasons

Why do we have different seasons? This lecture looks at the consequences of the tilt of the Earth's rotation axis relative to its orbital plane (the Obliquity of the Ecli

Lecture 6: Daily and Annual Motions

Why do celestial objects appear to rise in the East and set in the West? How does this depend on where you are on the Earth, or the time of year? Today we set the heavens

Lecture 5: Mapping Earth and Sky

Where are we? Where is someplace else? How do I get from here to there? These are questions we need to answer both on the Earth and in the Sky to assign a location to a p

Lecture 4: Measuring the Earth

What is the shape and size of the Earth? This lecture traces historical ideas about the shape of the Earth, from ancient flat-Earth models to the compelling demonstration

Lecture 3: The Starry Night

What are the constellations, and how have they be named and used by many different cultures throughout human history? We will review the most basic feature of the night s

Lecture 2: Astronomical Numbers

Before we can begin our exploration of astronomy, we need to develop a common language for notating large numbers, and introduce the basic units of length, mass, and time

Welcome to Astronomy 161

Welcome to the Astronomy 161 Lecture Podcasts. This is a brief message from me explaining the podcasts, and welcoming new and old listeners. University. Lectures will beg