Astronomy 101 Exam 3 questions and Verified
Answers
Revolutions in the solar system - ANSWER Mostly Counterclockwise- comets can be both
Rotations in the solar system - ANSWER Mostly Counterclockwise. Clockwise=Venus
Between=Uranus
Milky Way rotation - ANSWER 200 km/s
Two clouds that are on adjacent circular orbits around the galaxy. What happens as they orbit?
- ANSWER The inside cloud will eventually pass the outside one
Molecular Clouds - ANSWER Cool and dense-short lived-can collapse and fragment
Cloud Core - ANSWER Contain a protostar-small and hot
Accretion disks - ANSWER dense, hot, short-lived
Protostar - ANSWER dense, compressed interior. stable structure due to Hydrostatic
Equilibrium: no more collapse when pressure matches weight of star
Hydrostatic Equilibrium - ANSWER Weight of material above pushes in an inward direction.
gravity and pressure balance out
Solar Nebular Theory - ANSWER • An enormous cloud of dust and gas collapses into multiple
cores. • cores starts to form a disk around a protostar. • Material in the disk clumps. • These
clumps (also called cores) draw in gas, turn into planets. • The protostar grows large enough to
turn into a young star, blowing away the disk, leaving the planets.
, The temperature of the proto-Earth was about 600 K, thus the Earth formed out of: - ANSWER
All substances that can condense at temperatures below 600 K.
The composition of the solar nebula is likely similar to: - ANSWER The Sun
F=ma - ANSWER external forces F on an object is equal to the mass m of that object multiplied
by the acceleration
William Herschel - ANSWER Discovered- Uranus and 4 Moons, Infrared Light • Telescopes
made: >400 • Symphonies written: 24
Ole Romer - ANSWER Ole Romer- Measured speed of light- 131,000 mpsecond
Hipparchus - ANSWER First comprehensive star catalog, rated stars on a six point scale of
brightness--which we still use.
Apparent Magnitude - ANSWER - smaller numbers= brighter (m)
Luminosity vs Brightness - ANSWER • Brightness is apparent—what we see. • Luminosity is
energy output/second—an intrinsic (absolute) measure
Absolute luminosity+magnitude - ANSWER Absolute luminosity is defined as the same as
apparent
Absolute magnitude (M) most negative= most luminous (brightest)
Brightness = Luminosity / distance2 • BUT! Don't use magnitudes in this equation • Use solar
luminosities instead - ANSWER Brightness=l/d^2
Answers
Revolutions in the solar system - ANSWER Mostly Counterclockwise- comets can be both
Rotations in the solar system - ANSWER Mostly Counterclockwise. Clockwise=Venus
Between=Uranus
Milky Way rotation - ANSWER 200 km/s
Two clouds that are on adjacent circular orbits around the galaxy. What happens as they orbit?
- ANSWER The inside cloud will eventually pass the outside one
Molecular Clouds - ANSWER Cool and dense-short lived-can collapse and fragment
Cloud Core - ANSWER Contain a protostar-small and hot
Accretion disks - ANSWER dense, hot, short-lived
Protostar - ANSWER dense, compressed interior. stable structure due to Hydrostatic
Equilibrium: no more collapse when pressure matches weight of star
Hydrostatic Equilibrium - ANSWER Weight of material above pushes in an inward direction.
gravity and pressure balance out
Solar Nebular Theory - ANSWER • An enormous cloud of dust and gas collapses into multiple
cores. • cores starts to form a disk around a protostar. • Material in the disk clumps. • These
clumps (also called cores) draw in gas, turn into planets. • The protostar grows large enough to
turn into a young star, blowing away the disk, leaving the planets.
, The temperature of the proto-Earth was about 600 K, thus the Earth formed out of: - ANSWER
All substances that can condense at temperatures below 600 K.
The composition of the solar nebula is likely similar to: - ANSWER The Sun
F=ma - ANSWER external forces F on an object is equal to the mass m of that object multiplied
by the acceleration
William Herschel - ANSWER Discovered- Uranus and 4 Moons, Infrared Light • Telescopes
made: >400 • Symphonies written: 24
Ole Romer - ANSWER Ole Romer- Measured speed of light- 131,000 mpsecond
Hipparchus - ANSWER First comprehensive star catalog, rated stars on a six point scale of
brightness--which we still use.
Apparent Magnitude - ANSWER - smaller numbers= brighter (m)
Luminosity vs Brightness - ANSWER • Brightness is apparent—what we see. • Luminosity is
energy output/second—an intrinsic (absolute) measure
Absolute luminosity+magnitude - ANSWER Absolute luminosity is defined as the same as
apparent
Absolute magnitude (M) most negative= most luminous (brightest)
Brightness = Luminosity / distance2 • BUT! Don't use magnitudes in this equation • Use solar
luminosities instead - ANSWER Brightness=l/d^2
