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Lecture 2: Spaceship Earth Man is…related inextricably to all reality, known and unknowable…plankton, a shimmering phosphorescence on the sea and the spinning planets and an expanding universe, all bound together by the elastic string of time. It is advisable to look from the tide pool to the stars and then back to the tide pool again. -- John Steinbeck
The Reason for Seasons Spring Equinox Summer Solstice Winter Solstice Fall Equinox
Eclipses • Solar eclipse: occurs when the Moon’s shadow falls on the Earth • occurs only at new moon. • Lunar eclipse: occurs when the Moon passes through the Earth’s shadow • occurs only at full moon.
Solar Eclipses Total path Partial path Annular
The Mystery of Retrograde Motion Jupiter, shown at one month intervals
Astronomical Distance Units 1 parsec = 3.26 light years