ASTRONOMY 1010 UPDATED ACTUAL
QUESTIONS AND CORRECT ANSWERS
COMPLETE STUDY GUIDE
●● Size of visible Universe
Answer: 93 billion light years across
●● Chemical composition (by Mass)
Answer: 74% H, 24% He, 2% other elements
●● Average Temperature
Answer: 3k (-454 degrees F)
●● Temperature
Answer: Measure of energy associated with the random motion of
particles.
●● The Plank Era
Answer: First 10-43 seconds since the birth of the universe
●● The Grand Unified Theory (GUT) era
,Answer: Between 10-43 and 10-38 seconds; temperature falls from
10^32 to 10^29 K.
●● The Electroweak Era
Answer: Between 10-38 and 10-10 seconds; temperature falls from
10^29 K to 10^15 K.
●● The Particle Era
Answer: Between 10-10 and 10-3 seconds; temperature falls from 10^15
K to 10^12 K.
●● The Era of Nucleosynthesis
Answer: Between 0.001 seconds and 5 minutes; temperature falls from
10^12 K to 10^9 K.
●● The Era of Nuclei
Answer: Between 5 minutes and 380,000 years; temperature falls from
10^9 K to 3,000 K.
●● The Era of Atoms
Answer: Between 380,000 and about 1 billion years; temperature is
below 3,000 K.
●● The Era of Galaxies
, Answer: From about 1 billion years to present; temperature is between
60 K - 3 K.
●● Cosmic Microwave Background (CMB)
Answer: The observed CMB radiation shows that the early universe was
very hot and dense.
●● Temperature and Density Fluctuations
Answer: Existence of small fluctuations in the CMB radiation (1 part in
100,000) that would grow into galaxies.
●● Olbers' Paradox
Answer: The observational fact that the sky is not bright requires the
Universe to either be finite in size or finite in age.
●● Hubble's Law
Answer: The expansion of the Universe; galaxies are moving away from
us and from each other.
●● Hubble's Law equation
Answer: v = H0d, where v is the velocity of recession, H0 is Hubble's
constant, and d is the distance.
●● The Cosmological Principle
QUESTIONS AND CORRECT ANSWERS
COMPLETE STUDY GUIDE
●● Size of visible Universe
Answer: 93 billion light years across
●● Chemical composition (by Mass)
Answer: 74% H, 24% He, 2% other elements
●● Average Temperature
Answer: 3k (-454 degrees F)
●● Temperature
Answer: Measure of energy associated with the random motion of
particles.
●● The Plank Era
Answer: First 10-43 seconds since the birth of the universe
●● The Grand Unified Theory (GUT) era
,Answer: Between 10-43 and 10-38 seconds; temperature falls from
10^32 to 10^29 K.
●● The Electroweak Era
Answer: Between 10-38 and 10-10 seconds; temperature falls from
10^29 K to 10^15 K.
●● The Particle Era
Answer: Between 10-10 and 10-3 seconds; temperature falls from 10^15
K to 10^12 K.
●● The Era of Nucleosynthesis
Answer: Between 0.001 seconds and 5 minutes; temperature falls from
10^12 K to 10^9 K.
●● The Era of Nuclei
Answer: Between 5 minutes and 380,000 years; temperature falls from
10^9 K to 3,000 K.
●● The Era of Atoms
Answer: Between 380,000 and about 1 billion years; temperature is
below 3,000 K.
●● The Era of Galaxies
, Answer: From about 1 billion years to present; temperature is between
60 K - 3 K.
●● Cosmic Microwave Background (CMB)
Answer: The observed CMB radiation shows that the early universe was
very hot and dense.
●● Temperature and Density Fluctuations
Answer: Existence of small fluctuations in the CMB radiation (1 part in
100,000) that would grow into galaxies.
●● Olbers' Paradox
Answer: The observational fact that the sky is not bright requires the
Universe to either be finite in size or finite in age.
●● Hubble's Law
Answer: The expansion of the Universe; galaxies are moving away from
us and from each other.
●● Hubble's Law equation
Answer: v = H0d, where v is the velocity of recession, H0 is Hubble's
constant, and d is the distance.
●● The Cosmological Principle
