How do we make calendars? This lecture explores the astronomical
origins of our calendars. We start by discussing lunar and solar
calendars and their hybrids in history and tradition (for example, the
Islamic Lunar Calendar and the Hebrew Luni-Solar Calendar), and then
describe the Julian and Gregorian Calendar reforms that attempt to align
the calendar wi ... 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