Download Introduction to Astronomy

yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

History of astronomy wikipedia, lookup

Copernican heliocentrism wikipedia, lookup

Chinese astronomy wikipedia, lookup

Ursa Minor wikipedia, lookup

Aquarius (constellation) wikipedia, lookup

Astronomical unit wikipedia, lookup

History of Solar System formation and evolution hypotheses wikipedia, lookup

Formation and evolution of the Solar System wikipedia, lookup

Corvus (constellation) wikipedia, lookup

Equation of time wikipedia, lookup

Extraterrestrial skies wikipedia, lookup

Solar System wikipedia, lookup

Archaeoastronomy wikipedia, lookup

Dialogue Concerning the Two Chief World Systems wikipedia, lookup

Geocentric model wikipedia, lookup

Orrery wikipedia, lookup

Stellar kinematics wikipedia, lookup

Hebrew astronomy wikipedia, lookup

Tropical year wikipedia, lookup

Standard solar model wikipedia, lookup

Timeline of astronomy wikipedia, lookup

Miscellaneous announcements…
• Homework 1 due today by 5:00.
• Pick up Homework 2; solutions are on the web.
• Get started on a project soon, if you haven’t
• Astrophotographers: please see me after class.
• Questions on motion of the stars?
• Try out Sky View Café and/or Sky Chart III…
The Sun and the Seasons
6 September 2006
• Measuring angles in the sky
• How the sun moves through our sky
• Seasons
Measuring Angles
Motion of the Sun
• On any given day, the sun’s motion is
essentially the same as that of a star (rises in
the east, sets in the west).
• The sun’s motion doesn’t quite keep up with the
stars: It completes a 360º circle in 24 hours.
• With respect to the stars, the sun appears to
move once a year around a great circle, tipped
23.5º with respect to the celestial equator.
• In late June (summer solstice), the sun is
farthest north; in late December (winter
solstice), the sun is farthest south. In late
March and September (equinoxes), it’s on the
celestial equator.
Motion of the Sun
Facing south
Motion of the Sun
Sun’s apparent path among the stars is called the ecliptic
(A one-square-meter surface, directly facing the sun,
receives about 1000 watts of power.)