Astronomy Terms 1: History of Astronomy
celestial equator
located directly above the Earth's equator
gibbous
shape of the moon between the first quarter and full and the full and third quarter
What are the 3 most famous ancient astronomical structures?
1. Stonehenge; located in England, the statues line up with the sunrise on the solstices and equinoxes 2. Temple at Karnak; one of the Egyptian temples, it has its main chamber pointed in the direction of sunrise at winter solstice 3. Pyramids of Central America; the Mayans built pyramids so they could observe the heavens above the dense rain forest
celestial sphere
a clear plastic or glass sphere that represents the Earth and surrounding stars; this model places the Earth at the center of the sphere with the stars and Moon suspended above
planet
a massive body that orbits a star; comes from the Greek word "planetia," which means "wanderers"
zodiac
a narrow band on the celestial sphere that circles the heavens following the ecliptic which lies along its centerline; the ecliptic is tilted 23.5 degrees with respect to the celestial equator (IMAGE: https://www.tcnj.edu/~pfeiffer/AST161Lec/AST161Chaps/Zod&Eclip.png)
waxing
an increase in size
annual motion
appearance and disappearance of stars and constellations during the year due to the Earth changing in location as it orbits the sun
phases of the moon
deal with the amount of moon face visible to observers on earth; phases are as follows: new moon waxing crescent first quarter waxing gibbous full moon waning gibbous third quarter waning crescent
waning
decrease in size
constellations
groups of stars that seem to form some type of pattern or object, i.e. the ursa major and the ursa minor
celestial poles
points on the celestial sphere that do not move; there are two celestial poles, the north celestial pole and the south celestial pole located above the north and south poles respectively
equinox
the day on which the sun crosses the celestial equator; on this day the length of day and night are very close to the same
solstice
the day on which the sun pauses in its steady north to south motion and is stationary; soon the sun will reverse direction and begin to travel south to north
ecliptic
the path that the sun traces on the celestial sphere as it moves across the sky or, more correctly, as it appears to move through the constellations
crescent
the shape of the moon between the new and first quarter and the third quarter and the new
retrograde
the time in which planets move in a westwardly direction; all planets undergo this at some time
geocentric theory
this theory is based on the assumption that the Earth is the center of the universe; it was embraced strongly by the early Catholic Church and it was considered heresy to speak against this theory
heliocentric theory
this theory is based on the sun being the center of our solar system; the planets orbit the sun in an elliptical pathway