Terms Flashcards
Absolute Magnitude
how bright a star really is
Apparent Magnitude
how bright a star appears in our sky
A.M.
Ante Meridiem, meaning before the middle of the day
Arctic Circle
the latitude line where the sun doesn’t set on the summer solstice
Autumnal and Vernal Equinoxes
the two days of the year when the sun rises and sets on the celestial equator, making and equal amount of daylight and nighttime
Axis
the line around which a planetary body rotates
Day
the amount of time if takes for the earth to spin on its own axis one time
Galilean Moons
Jupiter’s four largest moons:
Europa
Io
Calisto
Ganymede
Geocentric Model
a model of the universe where earth is at the center and everything revolves around it
Horizon
from your perspective, the place where the sky meets the land
Jupiter
a planet named after the king-god of the Romans; with more moons than any other planet
Land of the Midnight Sun
a name for the region north of the arctic circle because the sun doesn’t set during the summer months
Light Year
the distance light travels in a year: about 5.8 trillion miles
Meridian
a line going from due south, strait over your head through the zenith, to due north; means “middle of the day”
Milky Way
a cloudy band circling the celestial sphere which is actually about 100 billion distant stars in our Milky Way Galaxy
Planet
a word meaning “wandering star;” the five classical planets are Mercury, Venus, Mars, Jupiter, and Saturn
P.M.
Post Meridiem, meaning after the middle of the day
Polar Night
the phenomenon where the sun doesn’t rise north of the arctic circle during the winter months
Retrograde Motion
when a planet stops going eastward against the background stars, turns around, and starts moving westward
Saturn
a planet named after the Roman god of agriculture and wealth; known for its rings
Summer Solstice
from the perspective of the Northern Hemisphere, the day of the year when the sun rises and sets at the northernmost place on the horizon
Terminator
the line on the surface of the globe where the night side of the earth meets the day side
Terminator
the line on the surface of the globe where the night side of the earth meets the day side
Titan
the largest moon of Saturn, known for its atmosphere and liquid lakes
Tropic of Cancer
the latitude line where the sun is at the zenith at high noon on the summer solstice
Tropic of Capricorn
the latitude line where the sun is at the zenith at high noon on the winter solstice
Tropics
the region between the Tropic of Cancer and the Tropic of Capricorn
Winter Solstice
from the perspective of the Northern Hemisphere, the day of the year when the sun rises and sets at the southernmost place on the horizon
Zenith
from your perspective, the part of the celestial sphere that is right over your head
