Astronomy 161, Introduction to the Solar System, is the first quarter ofa 2-quarter introductory Astronomy for non-science majors taught at TheOhio State University. This podcast presents audio recordings ofProfessor Richard Pogge's lectures from his Autumn Quarter 2007 class.All of the lectures were recorded live in 1000 McPherson Laboratory onthe OSU Main Campus in Columbus, Ohio.
Lecture 08: The Phases of the Moon28/09/2007
What are the Phases of the Moon? This lecture introduces the Moon and describes the monthly cycle of phases. Topics include synchronous rotation, apogee and perigee, the cycle of phases, and the sidereal and synodic month. Recorded 2007 Sep 28 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.
Lecture 07: The Four Seasons27/09/2007
Why do we have different seasons? This lecture explores the consequences of the tilt of the Earth's rotation axis relative to its orbital plane combined with the apparent annual motions of the Sun around the Ecliptic. The most important factor for determining whether it is hot or cold at a given location at different times in the year is "insolation": how much sunlight is spread out over the ground. This, combined with the different length of the day throughout the year, determines to total solar heating per day and so drives the general weather. It has nothing to do with how far away we are from the Sun at different times of the year. Finally, the direction of the Earth's rotation axis slowly drifts westward, taking 26,000 years to go around the sky. This "Precession of the Equinoxes" represents a tiny change that is still measureable by pre-telescopic observations, and means that at different epochs in human history there is a different North Pole star, or none at all! Recorded 2007 Sep 27 in 1000 Mc
Lecture 06: Daily and Annual Motions26/09/2007
Why do celestial objects appear to rise and set every day? How does this depend on where you are on the Earth, or the time of year? In today's lecture we we set the heavens into motion and review the two most basic celestial motions. Apparent Daily Motion reflects the daily rotation of the Earth about its axis. Apparent Annual Motion reflects the Earth's annual orbit around the Sun. We introduce the Ecliptic, the Sun's apparent annual path across the Celestial Sphere, and note four special locations along the Ecliptic: the Solstices and Equinoxes. This sets the stage for many of the topics of the rest of this section. Recorded 2007 Sep 26 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.
Lecture 05: Mapping Earth & Sky25/09/2007
Where are we? Where is someplace else? And how do I get there from here? These are questions we need to answer both on the Earth and in the sky to assign a location to a place or celestial object on the surface of a sphere. This lecture includes a review of angular units and the terrestrial system of latitude and longitude on the spherical Earth. We then define the Celestial Sphere, with its Celestial Equator and Poles, and begin to define an analogous coordinate system on the sky. An important wrinkle is that what part of the sky we see at any given time depends on both where we are on the Earth, and what date/time it is. This gives us the elements of the coordinate system we will need to begin our exploration of motions in the sky in the next lectures. Recorded 2007 Sep 25 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.
Lecture 04: Measuring the Earth24/09/2007
What is the shape and size of the Earth? This lecture traces historical ideas about the shape of the Earth, from ancient ideas of a Flat-Earth to Aristotle's compelling demonstrations in the 3rd century BC that the Earth was a sphere. We then discuss two famous classical measurements of the circumference of the Earth by Eratosthenes of Cyrene in the 3rd century BC and Claudius Ptolemy in the 2nd century AD. Recorded 2007 Sep 24 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.
Lecture 03: The Starry Night21/09/2007
What are the constellations? We will review the most basic feature of the night sky, the 6000 visible stars sprinkled about the sky, and introduce the idea of constellations, reviewing their history and uses by various cultures. Recorded 2007 Sep 21 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.
Lecture 02: Astronomical Numbers20/09/2007
What are our units of measure in astronomy? To begin our exploration of astronomy, we first need to develop a common language for notating large numbers, and introduce the basic units of length, mass, and time that we will use throughout the quarter. This lecture is a quick review of scientific notation and the metric system. For measuring the vast distances in astronomy, we need to introduce two special units: the Astronomical Unit for interplanetary distances, and the Light Year for interstellar distances. We end with a discussion of mass and weight, and the distinction drawn in physical measurements that differs (a little) from everyday usage. Recorded 2007 Sep 20 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.
Lecture 01: Introduction to Astronomy 16119/09/2007
What is Astronomy? What is Science? What is the course all about? Brief introductory remarks after going over course mechanics on the first day of Astronomy 161 for Autumn Quarter 2007. Recorded 2007 Sep 19 in 1000 McPherson Lab on the Columbus campus of The Ohio State University.
Welcome to Astronomy 161 for Autumn Quarter 200719/09/2007
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 begin on Wednesday, 2007 Sept 19, and run through Friday, 2007 Nov 30. New lectures will appear shortly before 6pm US Eastern Time each day there is a regular class. Recorded 2007 Sep 19 in 4037 McPherson Lab on the Columbus campus of The Ohio State University.