AST1 Introduction to Astronomy

1
(No Transcript)
2
(No Transcript)
3
Some imagination required!
4
(No Transcript)
5
(No Transcript)
6
(No Transcript)
7
When I Heard the Learn'd Astronomerby Walt
Whitman

• When I heard the learn'd astronomer,
• When the proofs, the figures, were ranged in
  columns before me,
• When I was shown the charts and diagrams, to add,
  divide, and measure them,
• When I sitting heard the astronomer where he
  lectured with much applause in the lecture-room,
• How soon unaccountable I became tired and sick,
• Till rising and gliding out I wander'd off by
  myself,
• In the mystical moist night-air, and from time to
  time,
• Look'd up in perfect silence at the stars.

8
(No Transcript)
9
Alternate models

• geocentric

• heliocentric

Which model is true?
10
demo
11
Diurnal motion

• Daily motion of all the objects in the sky

12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
Motion of the Earth

• Rotation about axis once every 23h56m (sidereal
  day)
• Revolution about sun once every 365.25 days
• Precession of axis every 26,000 yr
• All are counterclockwise (seen looking down from
  North Pole)

17
Precession
Takes 26,000 years
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
What causes seasons?

• Northern and Southern hemispheres have opposite
  seasons
• Earth closest to sun in January
• Varying distance of sun only changes intensity of
  light coming to earth by a few percent

24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
Summer Solstice

• Sun highest in sky
• shortest shadows
• Longest day
• Most direct sunlight
• warmest
• Sun is at the northernmost point of the ecliptic

Winter Solstice just the opposite!
29
Equinoxes

• Vernal (spring) and autumnal (fall)
• Equal hours of daylight darkness
• True everywhere on Earth!
• Sun is at the point where ecliptic crosses
  celestial equator
• Length of day changing fastest

30
analema
31
(No Transcript)
32
(No Transcript)
33
What phase is the moon in today?
34
(No Transcript)
35
animation
36
(No Transcript)
37
(No Transcript)
38
Eclipses

• Caused by shadows of earth moon
• Dont occur every month because of 5 inclination
  of moons orbit

39
(No Transcript)
40
(No Transcript)
41
(No Transcript)
42
(No Transcript)
43
(No Transcript)
44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
Web sites
Astronomy Picture of the Day http//antwrp.gsfc.na
sa.gov/apod/astropix.html Comins Kaufmann
(textbook) http//whfreeman.com/dtu6e others spac
e.com astronomydaily.com skyandtelescope.com