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 growsmaller 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.
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.
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
4) The Motion of the Moon
* The Moon appears to move eastward among the stars, returning to the same place after a Sidereal month
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.
Apparent solar day. Apparent solar time. Autumnal equinox. Ccelestial equator.Crescent phase. Declination. Direct motion. Diurnal. Diurnal circle. Ecliptic. Equatorial system. Full phase. Gibbous phase. Leap year. Local hour angle. Mean solar time. Meridian. New phase. Nodes. North celestial pole. North circumpolar region. Opposition. Quarter phase. Retrograde motion. Right ascension. Sidereal clocks.sidereal day. Sidereal month. South celestial pole. Summer solstice. Synodic month. Synodic period. Tropical year. Vernal equinox. Waning crescent. Waxing crescent. Winter solstice year. Zodiacal. Constellations
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