Physics 202: Introduction to Astronomy – Lecture 2

Carsten Denker

Physics DepartmentCenter for Solar–Terrestrial

Research

January 20, 2006 Center for Solar-Terrestrial Research

Prologue Constellations Celestial sphere North and south

celestial poles Celestial equator Celestial coordinates Declination and

right ascension Solar and sidereal

day

Ecliptic Zodiac Seasons Summer and winter

solstice Vernal and

autumnal equinox Tropical and

sidereal year Precession

January 20, 2006 Center for Solar-Terrestrial Research

Constellations in the Sky

January 20, 2006 Center for Solar-Terrestrial Research

Celestial Coordinates

January 20, 2006 Center for Solar-Terrestrial Research

Solar and Sidereal Day

January 20, 2006 Center for Solar-Terrestrial Research

Long-Term Changes ‒ Precession

January 20, 2006 Center for Solar-Terrestrial Research

Group ProblemHow and why does a day measured

by the Sun differ from a day measured by the stars?

Assume that the Earth would orbit the Sun in the opposite direction. How would that affect the solar and sidereal day?

January 20, 2006 Center for Solar-Terrestrial Research

The Orbit of the MoonPhasesNew, quarter, and full MoonSidereal month (27.3 days) and

synodic month (29.5 days)Solar and lunar eclipsesTotal, annular and partial solar

eclipseUmbra and penumbra

January 20, 2006 Center for Solar-Terrestrial Research

Lunar Phases

January 20, 2006 Center for Solar-Terrestrial Research

Lunar Eclipse

January 20, 2006 Center for Solar-Terrestrial Research

Solar Eclipse

January 20, 2006 Center for Solar-Terrestrial Research

Group ProblemWhy aren’t there lunar and solar

eclipses every month