Week 1-3 Quiz Flashcards
what are the three main things that the universe is composed of? What is so mysterious about two of them?
normal matter/energy, dark matter, and dark energy
normal matter/energy (humans, sun galaxies planet and stars) = makes up about 5% of the universe
dark matter (invisible, undetectable; only detected my gravitation) = makes up about 36% of universe
dark energy (A force that causes expansion of the universe to accelerate) = makes up about 68% of the universe
Where are we located in the universe?
our solar system is an a Milky Way galaxy that is a part of the local group galaxy 
how many stars are in our solar system?
there is one star = sun
what is light pollution? What kinds of problems does it cause?
less stars becoming visible due to artificial brightening of the night sky.
- street lights, satélites and other man-made sources cause
- affects natural life
Visible stars at night is less than two dozen
explain the difference between a constellation and an Asterism (name most famous asterism)
Constellations = Pattern of stars named after mythological animals, characters, or objects (human invention with no physical significance: 88 constellations.
Asterism: nickname given to a group of stars; part of an established constellation (eg big dipper) 
how many constellations are there? What percentage of the sky is covered by constellations?
there are 88 constellations
what is the celestial sphere? What are the key features (or locations) on it?
 Celestial sphere = an imaginary sphere of stars surrounding earth (helps Identify where things are in the sky)
key features:
Celestial poles = Extension of earths north and south poles on the celestial sphere (north celestial pole; south celestial pole)
celestial equator = projection of earth’s equator onto the celestial sphere (can you find an objects position on surface of earth) 
what would be the altitude of the north star as seen from the north pole? The equator? San Marcos?
North pole = 90 degrees
Equator = 0 degrees
San marcos = 33 degrees
which parts of the earth can you see most of the celestial sphere?
The equator
what is the difference between rotation and revolution?
rotation = Spinning on axis; Causes day and night
Revolution =  orbit around sun (1 year)
One earth rotation equals one ______.
One earth revolution equals one ______.
earth rotation = 24 hours
earth revolution = 1 year
What is a solar day and a Sidereal day? Why are they different? Which is longer and why?
solar day = How long it takes the sun to complete two successive crossing of meridian
durations : 24 hours
sidereal day = The time it takes for two successive crosses of a celestial object across meridan (other than sun, moon or planets)
duration: 23 hours & 56 mins
stellar objects rise about four minutes earlier each night
what is the Ecliptic? What is the collective name for the constellations found along the Ecliptic?
ecliptic = The apparent annual path of the sun takes against the stars (planets aligned)
it (elliptic) runs through the 12 constellations of the zodiac
why does earth have seasons?
it is not distance but it’s the fact that we have an axis tilt (23.5)
depends on where and how high or low the sun is in the hemisphere (how bright or intense the sunlight is striking a surface) 
smaller area = more intensity
bigger area = less intensity
what do the word solstice and equinox mean? What happens at solstice and an equinox? When do they occur?
longest day: short night (vice versa)
winter and summer
solstice = “sun stands still”
equinox = “equal night”
spring and autumn
night and day about equal (12 hrs)
