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