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Tahsiri: Lecture notes :
Kenealy: Read chapters (1-6).
Please click on the Virtual library www reference guides after the red arrow for further Discussions and Illustrations on the important terms relevant to my lectures.
1) The Daily Motion of thr Sky
* The daily or diurnal, westward paths of stars are circles that are centered on the north celestial pole. The diurnal circles grow smaller for stars that are nearer the north celestial pole.
* The celestial equator: is a line on the
celestial sphere that divides it into northern and southern hemispheres.
* The Equtoral System: is used to locate stars on the celestial
sphere. This system resembles the terrestrial system of longitude
and latitude. In the equatorial system,
* Declination describes the angular distance
of a star north or south of the celestial equator.
* Right ascension describes the east-west location of a star on
the celestial sphere.
a) Illustrations
(1) Diurnal
Motion (2) The
Daily Motion of the Celestial Sphere (3) Daily
Motion (4) Solar
Motion (5) Prictice
Questions (6) Motion
of Sun and Stars (7) Diurnal
Motion Focus Questions (8)
Right ascention and Declination (9) Right
Ascension & Declination (10) Right
Ascension Converting between RA angles in degrees and in hours:minutes
2) The Apparent Motion of the Sun
* Ecliptic: The plane of the Earth's orbit
about the Sun. As a result of the Earth's motion, the Sun appears
to move eastward among the stars, following a path that is also
called the ecliptic.
and its motion is repeated annually.
* The ecliptic is inclined with respect
to the celestial equator, so the declination of the Sun varies
during the year.
* The Season: Changes in the declination of the Sun
produce an annual pattern of change in its rising and setting
points as well as change in its altitude at noon. These changes
are responsible for the Seasons.
* Apparent Solar Time: Time kept according to the actual position of the Sun in the sky. Apparent solar noon occurs when the Sun crosses an observer's meridian. The variable rate of the Sun's motion on the ecliptic causes changes in the length of the solar day throughout the year.
b) Illustrations(1) The
Ecliptic (2) Ecliptic
Plane (3) The
Ecliptic (4) Ecliptic
and the motion of the Sun (5) The
Earth, Sun, and Moon
(6) Motion
of the Sun
3) The phases of the Moon
* The phase of the Moon happen because the part of the Moon's
illuminated hemisphere that we see varies throughout a Synodic
month .
* The length of a synotic month is 29.53 days between successive occurrences of the same phase of the Moon
c) Illustrations(1) Moon
Phases (2) Virtual
Reality Moon Phase Pictures (3)
Phase
of the Moon (4) Phases
of the Moon and Percent of the Moon Illuminated (5) Moon Phases for
20001 (6) Synaotic
and Sidereal Mounth (7) Sydereal
and Synotic Mounth (8) Synotic&Sidereal
(9) The
Sidereal Month
4) The Motion of the Moon
* The Moon appears to move eastward among the stars, returning to the same place after a Sidereal month
d) Illustrations(1)
Motion
of the Moon (2) Homework
with Solutions (3) Daily
Motion of the Moon
5) The Motions of the Planets
* The planets usually appear to move eastward among the stars. However, at regular intervals they appear to move westward during periods of Retrograde motion. The motions of the planets among the stars are quite complex.
f) Illustrations(1)
The
retrograde motion of planets (2) Retrograde
Motion (3) Retrograde
Motion Simulation (4) Retrograde
Motion with Animation
1. Which of the following coordinates describes the angular distance of an object north or south of the celestial equator? Declination
2. Suppose there is a star which rises at 10 p.m. tonight. At
what time did it rise one month ago? Midnight
3. An observer in Quito, Ecuador (latitude 0 deg) sees the Sun
at the zenith at noon on which day(s)? Spring and Fall equinox
4. The sun moves eastward among the stars at the rate of about
one degree per day
5. The time that your wristwatch keeps is mean solar time
6. The occurrence of seasons on the Earth is due to the Earth's
axis being inclined to the ecliptic
7. At approximately what time does the new moon rise? Sunrise
8. Relative to the stars, the moon moves eastward
9. In which of the following circumstances is it possible to observe
the full moon? Rising at sunset
10. Which of the following is true of the motion of the planet
Mars among the stars? retrograde loops always are separated by
the same interval of time
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