Astro 5 UCLA Midterm (Hansen)
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Geocentric Model - CORRECT ANSWER - -earth at center of celestial sphere
-problem: retrograde motion
Heleocentric Model - CORRECT ANSWER - -originally considered, but then rejected
-should have predicted stellar parallax (could not detect it with their level of precision)
Epicycles - CORRECT ANSWER - -addressed retrograde motion
-each planet revolves around a deferent as it orbits
Copernican Principle - CORRECT ANSWER - -revived heleocentric model
-states that we occupy no special place or time in universe
Keplers 3 laws - CORRECT ANSWER - -orbits are elliptical around the sun at one focus
-the closer you are to the sun, the faster you go
-mathematical relationship between period of orbit and distance from the sun
Discovery science - CORRECT ANSWER - -exploring and gathering data
Hypothesis-driven science - CORRECT ANSWER - -propose ideas to be tested
Theory - CORRECT ANSWER - -a model that describes the underlying principles which
give rise to observed phenomena
,Occam's Razor - CORRECT ANSWER - -usually the simplest explanation is the correct
one
Nuclear burning/fusion - CORRECT ANSWER - -fusing lighter elements into heavier
Spectroscopy - CORRECT ANSWER - -each element has a characteristic spectral
fingerprint corresponding to absorption/emission at particular wavelengths
-provides info about the temperature and composition of a radiating body
Astronomical background - CORRECT ANSWER - -universe began much hotter and
denser than today
- expanded and cooled to current state through 14 Ga
Galaxy creation - CORRECT ANSWER - -originally a nebula (cloud of dust and gas)
-created by clumps of material falling together under mutual gravity
-the collapsing galaxy contains both dark matter and gas
-gas cools and clump together, eventually collapses to form stars
-composition of original gaseous material: 75% H, 25% He
-formation of a star requires contraction which results of spinning of material to form a disk
Planet formation - CORRECT ANSWER - - formation of a star leaves a disk of gas and
dust orbiting it
-the dust grows by accreting other durst; forms pebbles which become large bodies
- if planet is large enough, it can gravitationally capture gas from surrounding nebula
Origin of elements - CORRECT ANSWER - -stars are like nuclear reactors; their energy
comes from fusing hydrogen and helium, and then helium with itself and so on
-stars end their lives by losing mass
-nuclear processed material is ejected back into the interstellar medium
, -then swept up and takes part in the collapsing of material to form a new star
Mercury - CORRECT ANSWER - - much smaller than earth
- but much higher density
- MUCH hotter surface
- no atmosphere
Venus - CORRECT ANSWER - - similar size to earth
- Too dense of an atmosphere which keeps the surface very hot
Earth - CORRECT ANSWER - - habitable because of presence of liquid water
Mars - CORRECT ANSWER - - 10% mass of earth
- 50% further than earth
- very thin atmosphere today, maybe have been thicker in the past (habitable)
Jupiter - CORRECT ANSWER - - 300x as massive as earth
- mostly gas, hydrogen and helium
- 4 large moons with solid surfaces
Saturn - CORRECT ANSWER - - 100x as massive as earth
- orbited by a ring system and one large moon
Uranus - CORRECT ANSWER - - 15x as massive as earth
- equal parts rock and ice
- tilted on its spin axis relate to the orbital plane (only planet to do this, possibly do to a big
collision)
UPDATED ACTUAL Exam Questions and
CORRECT Answers
Geocentric Model - CORRECT ANSWER - -earth at center of celestial sphere
-problem: retrograde motion
Heleocentric Model - CORRECT ANSWER - -originally considered, but then rejected
-should have predicted stellar parallax (could not detect it with their level of precision)
Epicycles - CORRECT ANSWER - -addressed retrograde motion
-each planet revolves around a deferent as it orbits
Copernican Principle - CORRECT ANSWER - -revived heleocentric model
-states that we occupy no special place or time in universe
Keplers 3 laws - CORRECT ANSWER - -orbits are elliptical around the sun at one focus
-the closer you are to the sun, the faster you go
-mathematical relationship between period of orbit and distance from the sun
Discovery science - CORRECT ANSWER - -exploring and gathering data
Hypothesis-driven science - CORRECT ANSWER - -propose ideas to be tested
Theory - CORRECT ANSWER - -a model that describes the underlying principles which
give rise to observed phenomena
,Occam's Razor - CORRECT ANSWER - -usually the simplest explanation is the correct
one
Nuclear burning/fusion - CORRECT ANSWER - -fusing lighter elements into heavier
Spectroscopy - CORRECT ANSWER - -each element has a characteristic spectral
fingerprint corresponding to absorption/emission at particular wavelengths
-provides info about the temperature and composition of a radiating body
Astronomical background - CORRECT ANSWER - -universe began much hotter and
denser than today
- expanded and cooled to current state through 14 Ga
Galaxy creation - CORRECT ANSWER - -originally a nebula (cloud of dust and gas)
-created by clumps of material falling together under mutual gravity
-the collapsing galaxy contains both dark matter and gas
-gas cools and clump together, eventually collapses to form stars
-composition of original gaseous material: 75% H, 25% He
-formation of a star requires contraction which results of spinning of material to form a disk
Planet formation - CORRECT ANSWER - - formation of a star leaves a disk of gas and
dust orbiting it
-the dust grows by accreting other durst; forms pebbles which become large bodies
- if planet is large enough, it can gravitationally capture gas from surrounding nebula
Origin of elements - CORRECT ANSWER - -stars are like nuclear reactors; their energy
comes from fusing hydrogen and helium, and then helium with itself and so on
-stars end their lives by losing mass
-nuclear processed material is ejected back into the interstellar medium
, -then swept up and takes part in the collapsing of material to form a new star
Mercury - CORRECT ANSWER - - much smaller than earth
- but much higher density
- MUCH hotter surface
- no atmosphere
Venus - CORRECT ANSWER - - similar size to earth
- Too dense of an atmosphere which keeps the surface very hot
Earth - CORRECT ANSWER - - habitable because of presence of liquid water
Mars - CORRECT ANSWER - - 10% mass of earth
- 50% further than earth
- very thin atmosphere today, maybe have been thicker in the past (habitable)
Jupiter - CORRECT ANSWER - - 300x as massive as earth
- mostly gas, hydrogen and helium
- 4 large moons with solid surfaces
Saturn - CORRECT ANSWER - - 100x as massive as earth
- orbited by a ring system and one large moon
Uranus - CORRECT ANSWER - - 15x as massive as earth
- equal parts rock and ice
- tilted on its spin axis relate to the orbital plane (only planet to do this, possibly do to a big
collision)
