Astronomy 161 - Introduction to Solar System Astronomy - Autumn 2007

By Richard PoggeScience Education Courses Natural Sciences Astronomy

Astronomy 161 - Introduction to Solar System Astronomy - Autumn 2007 episodes

September 28, 2007 Lecture 08: The Phases of the Moon
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.
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September 27, 2007 Lecture 07: The Four Seasons
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 McPherson Lab on the
Columbus campus of The Ohio State University.
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September 26, 2007 Lecture 06: Daily and Annual Motions
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.
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September 25, 2007 Lecture 05: Mapping Earth & Sky
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.
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September 24, 2007 Lecture 04: 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 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.
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September 21, 2007 Lecture 03: The Starry Night
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.
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September 20, 2007 Lecture 02: Astronomical Numbers
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.
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September 19, 2007 Lecture 01: Introduction to Astronomy 161
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.
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September 19, 2007 Welcome to Astronomy 161 for Autumn Quarter 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.
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