section 1 Flashcards
geocentric model
everything orbit earth in sphere patterns
proposed by aristotle
heliocentric model
what was it missing?
everything orbits sun in sphere patterns
proposed by copernicus
Kepler: orbit of planets isnt in spheres but elipses
solstice
longest/shortest day of the year
dec 21 (winter) and june 21 (summer)
equinox
2 days with equal amounts of night/day time
march 21 (spring) and sept 21 (autumn)
tools used before telescopes?
can probably skip
quadrant: measures star height above horizon
astrolabe: makes charts of star positions
cross staff: meausre angle between moon and any star
Astronomical Units
(AUs)
used for distances inside our solar system
distance: centre of the earth to centre of the sun
light years
used for distances beyond our solar system
distance: that light travels in one year (9.5 trillion km)
what are stars
what defines their colour?
hot, glowing ball of gas (hydrogen) giving off tons of light energy
hot = blue
cool = red
sun-like and massive star life cycle
birth of a star
cloud nebula - collapses n mass/temp increase when more material is drawn in
protostar - when core gets hot enough to glow
sun-like and massive star life cycle
main sequence of a star
protostar is hot enough for nuclear fusion
sun-like star life cycle
old age of a star
massive AND sunlike
star funs out of hydrogen (is dying)
stabilizes with gravity
leads to it expanding into red giant
MASSIVE; becomes red SUPERgiant
sun-like star life cycle
death and remnants of sun-like stars
core temp is too cool so it collapses on itself
shrinks untill it becomes white dwarf
fades slowly into black dwarf
nuclear fusion
hydrogen → helium
massive star life cycle
death and remnants of massive star
fusion stops and star suddenly collapses on itself (SUPERNOVA)
if it survives explosion it can be a BLACK HOLE or NEUTRON STAR
neutron star: rapidly spinning ball of neutrons
black hole: dense remnants of star with strong gravity
constellations
unoffical recognized star groups
groupings of stars seen as patterns in the night sky
asterisms