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Astro 101 Exam 2 Questions And Answers
|Latest 2025 | Guaranteed Pass.
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
1
, ©FYNDLAY 2024/2025 ALL RIGHTS RESERVED 1:25PM A+
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
Black body/thermal radiation - Answer✔absorbs all incident electromagnetic radiation The
color of a black body is a quick measure of its temperature. • red = ~3000 K • yellow = ~5500 K
• blue = ~30,000 K
Wien's displacement law - Answer✔states that the black body radiation curve for different
temperatures peaks at a wavelength inversely proportional to the temperature.
Two stars same size and distance which is hotter - Answer✔Which peak is higher
Which of these stars in
Orion is most luminous?
star m M distance
1 Rigel 0.18 -6.69 773
2 Betelgeuse 0.42 -6.02 643
3 Bellatrix 1.64 -2.72 242
4 Alnilam 1.69 -6.38 - Answer✔1. Rigel- Most negative=most luminous
Two stars at the same distance, which is more
luminous? - Answer✔Whichever is putting out more light at all wavelengths
Two stars at the same distance, which looks redder? - Answer✔Which peak is in the red section
600-700nm
Two stars at the same distance, which emits more red
2
Astro 101 Exam 2 Questions And Answers
|Latest 2025 | Guaranteed Pass.
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
1
, ©FYNDLAY 2024/2025 ALL RIGHTS RESERVED 1:25PM A+
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
Black body/thermal radiation - Answer✔absorbs all incident electromagnetic radiation The
color of a black body is a quick measure of its temperature. • red = ~3000 K • yellow = ~5500 K
• blue = ~30,000 K
Wien's displacement law - Answer✔states that the black body radiation curve for different
temperatures peaks at a wavelength inversely proportional to the temperature.
Two stars same size and distance which is hotter - Answer✔Which peak is higher
Which of these stars in
Orion is most luminous?
star m M distance
1 Rigel 0.18 -6.69 773
2 Betelgeuse 0.42 -6.02 643
3 Bellatrix 1.64 -2.72 242
4 Alnilam 1.69 -6.38 - Answer✔1. Rigel- Most negative=most luminous
Two stars at the same distance, which is more
luminous? - Answer✔Whichever is putting out more light at all wavelengths
Two stars at the same distance, which looks redder? - Answer✔Which peak is in the red section
600-700nm
Two stars at the same distance, which emits more red
2
