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ASTRO 7N FINAL EXAM LATEST 2025 / 2026 ACTUAL
EXAM WITH COMPLETE QUESTIONS AND CORRECT
DETAILED ANSWERS (100% VERIFIED ANSWERS)
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What is the sun comprised of? - Answer-Mostly gas- hydrogen 73% and helium 25%
Forces of the sun - Answer-inward force- balance of gravity makes it stable and outward force- gas pressure in its hot interior
What causes gas pressure and how hot are these reactions in the Sun? - Answer-Nuclear fusion in the Sun's core, 15 million degrees kelvin
Diameter and mass of the Sun compared to Earth - Answer-Diameter is 109 X and mass is 333,000 X
Luminosity of the sun - Answer-4 x 10^24 100 Watt lightbulbs
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How much of the solar system's mass is in the sun? - Answer-99.9%
Life of the sun - Answer-4.5 billion years, will continue for another 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; have 11 year cycles
nuclear fusion - Answer-long lasting source of energy in stars; 4 protons combine to make heluium-4 (2 protons and 2 neutrons) and release energy in gamma rays
Proton-Proton Chain - Answer-2 protons collide at very high speed, stick together and one changes into a neutron, ends with a Deuterium nucleus
Deuterium nucleus collides with another proton and makes a helium-3 Nucleus, more energy is released
- Helium-3 nuclei combine to make Helium 4 Nucleus
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Energy output from p-p chain - Answer-E=mc^2
Which has a higher mass and why :Helium-4 nucleus or 4
protons - Answer-4 protons; some mass is converted into energy in the form of gama rays in the formation of a Helium-4 nucleus
Core - Answer-at the center, high density and temp., nucleur fussion occurs here and gama rays are produced
Radiative zone - Answer-photons are repeatedly re- absorbed and re-emitted; energy in an individual proton can take on avg 170,000 years to pass through
convective zone - Answer-hot gas rises and cold gas sinks; light traverses in about one week
photosphere - Answer-temperature 5,780 K; this is the "surface" of the Sun that we see; photons have been converted to visible wavelengths; can see "granules" due to convection bringing material up and down in cells
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