Chapter 2 Discovering the Universe for Yourself. Chapter Outline Patterns in the Night Sky The Reason for Seasons The Moon, Our Constant Companion The Ancient Mystery of the Planets. 2/7/2005 2:55 PM. 2.1 Patterns in the Night Sky. What are constellations?
Patterns in the Night Sky
The Reason for Seasons
The Moon, Our Constant Companion
The Ancient Mystery of the Planets
2/7/2005 2:55 PM
What are constellations?
How do we locate objects in the sky?
Why do stars rise and set?
Why don’t we see the same constellations throughout the year?
Red lines mark constellation boundaries
(altitude = 0o)
(azimuth = 0o)
(azimuth = 90o)
(azimuth = 270o)
(azimuth = 180o)
Angular measure is in degrees, minutes, and seconds of arc
1 degree = 60 arcminutes
1 arcminute = 60 arcseconds
What causes the seasons?
How do we mark the progression of the seasons?
Does the orientation of the Earth’s axis change with time?
Why do we see phases of the Moon?
What causes eclipses?
What was once so mysterious about the movement of planets in our sky?
Why did the ancient Greeks reject the real explanation for planetary motion?
Greatest Western Elongation
Greatest Eastern Elongation
EarthInferior Planet Configurations
One Month Later
Month 1Synodic and Sidereal Month