stars pt 2

could we see a galaxy is 20 billion light-years away 

• no, because it would be beyond the bounds of our observable 

an astronomical unit is

• earths average distance from the sun

what is false about the cosmic calendar illustration

• humans have been around for relatively very long time period when compared astronomical event 

a television advertisement claiming that a product is light-years ahead of its not make sense because 

• it would take a long time for the product to be seen 

winter solstice to verbal equinox is 

• 3 months 

astronomers use “constellation” to mean

• an entire region of the sky

solar vs sidereal day difference is because

• earths orbit plus rotation makes solar day slightly longer 

moons 360 orbit time is called

• sidereal month 

an asterism is

• a recognizable star pattern (big dipper)

if theres a total lunar. eclipse, the moons phase is

• full 

in ptolemaic model, retrograde motion happens when

• planets go backwards in epicycles around earth 

who discovered law of gravitation

• newton 

gravitational force depends on masses and

• distance between their centers

if earth-sun distance doubled, force would

• decrease by factor of 4 (inverse-square law)

resolution 12 cm vs 4 cm mirror

• 3x better resolution (angular resolution = diameter) 

refraction occurs when

• light enters a new medium and changes direction 

which is not a EM radiation

• cosmic rays 

double slit + photoelectric effect established

• light has wave-particle duality

nucleus contains

• protons and neutrons 

best way to determine chemical composition

• from its spectrum

an ion is when

• number of protons = number electrons 

emission spectra created when

• electrons drop energy levels, emit photons

star formation order →gas cloud→jeans instability→protostar→star. third is

• protostar 

exoplanet detection using relativity effect 

• microlensing 

which does not trigger jeans instability 

• protostars accreting has/dust doesn’t compress other clouds

conservation of angular momentum caused

• spinning faster and flattening into a disk

moon formed by

• giant impact with mars-sized body 

rock/metal debris smaller than asteroids

• meteoroids 

jupiter formation/evolution

• formed past snow line, migrated inward, then pushed outward by saturn