What time is it? Telling time is the oldest practical application of
astronomy. Today's lecture is the first of a 2-part lecture on the
astronomical origins of our methods of keeping time and making
calendars. This lecture reviews the divisions of the year into the
solstices, equinoxes, and cross-quarter days, the division of the year
into months by moon ... Show More
Oct 2007
Lecture 12: The Wanderers
How do the planets move across the sky? This lecture discusses the motions of the 5 naked-eye planets (Mercury, Venus, Mars, Jupiter, and Saturn) as seen from the Earth. We introduce the major configurations of the planets, and then discuss their apparent retrograde motions. The ... Show More
42m 34s
Mar 2006
Lecture 44: Life, the Universe, and Everything (Life Part II)
How can we search for extraterrestrial intelligence, and what are we looking for? This second part of a 2-part lecture picks up where we left off yesterday by examining SETI, the Search for ExtraTerrestrial Intelligence, and reviews what we might look for and how. We will use thi ... Show More
45m 56s
Sep 2006
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 that we will use throughout the quarter.
We will first re-introduce the basic metric system, explaining how t ... Show More
43m 29s