Chapter 0 Flashcards
(35 cards)
north celestial pole
the point where Earth’s rotation axis intersects the celestial sphere in the northern hemisphere
south celestial pole
the extension of earth in the opposite direction
celestial equator
midway between the north and south celestial poles
celestial coordinates
location with longitude and latitude
declination and right ascension
the celestial analogs of latitude and longitude
solar day
the rhythm of day and night is central to our lives, so it is not suprising that the period of time from one sunrise to the next , the 24 hour time period is our social time unit
diurnal motion
the daily progress of the Sun and other stars across the sky
sidereal day
a day measured by the stars
ecliptic
the apparent motion of the Sun on the sky traces out a path on the celestial sphere
zodiac
the special significance of stars
summer solstice
the point on the ecliptic where the Sun is at its northernmost point above the celestial equator
winter solstice
the Sun is at its southernmost point below the celestial equator
equinoxes
the two points where the ecliptic interescts the celestial equator, that is , where Earths rotation axis is perpendicular to the line joining earth to the Sun
autumnal equinox
when the Sun crosses from the northern into the southern celestial hemisphere
vernal equinox
occurs in spring, as the Sun crosses the celestial equator moving north
tropical year
the interval of time from one vernal equinox to the next, 365.242 days
phases
illustrates the appearance of the moon at different times in the month
quarter moon
one week after new moon, half of the lunar disk can be seen
full moon
the moon continues to wax, passing through the gibbous phase until, 2 weeks after Moon wanes
sidereal month
the moons position in the sky changes with respect to the stars
synodic month
the time required for the Moon to complete a full cycle of phases
lunar eclipse
earths shadow sweeps across the moon, temporarily blocking the Sun’s light and darkening the Moon
partial eclipse
the shadow of earth never completely covers the moon
total eclipse
the entire lunar surface is obscured
