Astro 101 Exam 2 ALREADY PASSED
Revolutions in the solar system - =Mostly Counterclockwise- comets can be both
Rotations in the solar system - =Mostly Counterclockwise. Clockwise=Venus Between=Uranus
Milky Way rotation - =200 km/s
Two clouds that are on adjacent circular orbits around the galaxy. What happens as they orbit?
- =The inside cloud will eventually pass the outside one
Molecular Clouds - =Cool and dense-short lived-can collapse and fragment
Cloud Core - =Contain a protostar-small and hot
Accretion disks - =dense, hot, short-lived
Protostar - =dense, compressed interior. stable structure due to Hydrostatic Equilibrium: no
more collapse when pressure matches weight of star
Hydrostatic Equilibrium - =Weight of material above pushes in an inward direction. gravity and
pressure balance out
Solar Nebular Theory - =• 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: - =All
substances that can condense at temperatures below 600 K.
, The composition of the solar nebula is likely similar to: - =The Sun
F=ma - =external forces F on an object is equal to the mass m of that object multiplied by the
acceleration
William Herschel - =Discovered- Uranus and 4 Moons, Infrared Light • Telescopes made: >400 •
Symphonies written: 24
Ole Romer - =Ole Romer- Measured speed of light- 131,000 mpsecond
Hipparchus - =First comprehensive star catalog, rated stars on a six point scale of brightness--
which we still use.
Apparent Magnitude - =- smaller numbers= brighter (m)
Luminosity vs Brightness - =• Brightness is apparent—what we see. • Luminosity is energy
output/second—an intrinsic (absolute) measure
Absolute luminosity+magnitude - =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 - =Brightness=l/d^2
Black body/thermal radiation - =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
Revolutions in the solar system - =Mostly Counterclockwise- comets can be both
Rotations in the solar system - =Mostly Counterclockwise. Clockwise=Venus Between=Uranus
Milky Way rotation - =200 km/s
Two clouds that are on adjacent circular orbits around the galaxy. What happens as they orbit?
- =The inside cloud will eventually pass the outside one
Molecular Clouds - =Cool and dense-short lived-can collapse and fragment
Cloud Core - =Contain a protostar-small and hot
Accretion disks - =dense, hot, short-lived
Protostar - =dense, compressed interior. stable structure due to Hydrostatic Equilibrium: no
more collapse when pressure matches weight of star
Hydrostatic Equilibrium - =Weight of material above pushes in an inward direction. gravity and
pressure balance out
Solar Nebular Theory - =• 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: - =All
substances that can condense at temperatures below 600 K.
, The composition of the solar nebula is likely similar to: - =The Sun
F=ma - =external forces F on an object is equal to the mass m of that object multiplied by the
acceleration
William Herschel - =Discovered- Uranus and 4 Moons, Infrared Light • Telescopes made: >400 •
Symphonies written: 24
Ole Romer - =Ole Romer- Measured speed of light- 131,000 mpsecond
Hipparchus - =First comprehensive star catalog, rated stars on a six point scale of brightness--
which we still use.
Apparent Magnitude - =- smaller numbers= brighter (m)
Luminosity vs Brightness - =• Brightness is apparent—what we see. • Luminosity is energy
output/second—an intrinsic (absolute) measure
Absolute luminosity+magnitude - =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 - =Brightness=l/d^2
Black body/thermal radiation - =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
