ASTRO 7N ACTUAL EXAM SOLVED
QUESTIONS COMPLETE PREPARATION
RESOURCE
●● why is the sun stable?
Answer: balance of gravity (inward force) and gas pressure in hot
interior (outward force)
●● sun compared to the earth (SIZE)
Answer: diameter is 109 x earth's, mass is 333,000 x earth's
●● luminosity of the sun
Answer: 4x10^24 100W lightbulbs
●● what percent of all mass of the solar system is the sun
Answer: 99.9%
●● how long has the sun been shining and how long will it continue
Answer: 4.5 billion years, 5.5 billion years
●● sunspots
, Answer: slightly-cooler regions on the sun's surface due to magnetic
activity preventing hot material from rising in that region (11 year
cycles)
●● nuclear fusion
Answer: long-lasting source of energy in stars: 4 protons combine to
make helium-4 (2 protons and 2 neutrons) and release energy in gamma
rays
●● proton-proton chain Step 1
Answer: 2 protons collide at VERY high speeds and stick together, one
changes into neutron and ends with a deuterium nucleus (2H: 1 proton
and 1 neutron, bound together) plus released energy
●● proton-proton chain step 2
Answer: deuterium nucleus from step 1 collides with another proton and
makes a helium-3 nucleus (2 protons and 1 neutron bound together) plus
more released energy
●● proton-proton chain step 3
Answer: two helium-3 nuclei combine to make a helium-4 nucleus (2
protons and 2 neutrons bound together) releasing 2 protons int he
process and excess energy
●● energy from the output of the p-p chain comes from
QUESTIONS COMPLETE PREPARATION
RESOURCE
●● why is the sun stable?
Answer: balance of gravity (inward force) and gas pressure in hot
interior (outward force)
●● sun compared to the earth (SIZE)
Answer: diameter is 109 x earth's, mass is 333,000 x earth's
●● luminosity of the sun
Answer: 4x10^24 100W lightbulbs
●● what percent of all mass of the solar system is the sun
Answer: 99.9%
●● how long has the sun been shining and how long will it continue
Answer: 4.5 billion years, 5.5 billion years
●● sunspots
, Answer: slightly-cooler regions on the sun's surface due to magnetic
activity preventing hot material from rising in that region (11 year
cycles)
●● nuclear fusion
Answer: long-lasting source of energy in stars: 4 protons combine to
make helium-4 (2 protons and 2 neutrons) and release energy in gamma
rays
●● proton-proton chain Step 1
Answer: 2 protons collide at VERY high speeds and stick together, one
changes into neutron and ends with a deuterium nucleus (2H: 1 proton
and 1 neutron, bound together) plus released energy
●● proton-proton chain step 2
Answer: deuterium nucleus from step 1 collides with another proton and
makes a helium-3 nucleus (2 protons and 1 neutron bound together) plus
more released energy
●● proton-proton chain step 3
Answer: two helium-3 nuclei combine to make a helium-4 nucleus (2
protons and 2 neutrons bound together) releasing 2 protons int he
process and excess energy
●● energy from the output of the p-p chain comes from
