ASTRO 7N Exam 2 questions with complete solutions 2024

ASTRO 7N Exam 2Sun's composition - correct answer Composed mostly of gas - hydrogen (73% by mass) and helium (25% by mass)` Sun's stability - correct answer Stable due to balance of gravity (inward force) and gas pressure in its hot interior (outward force) Sun's gas pressure - correct answer Gas pressure provided by nuclear fusion reactions in the Sun's core, going on at a temperature of 15 million degrees Kelvin Sun's diameter and mass compared to Earth - correct answer Diameter: 109*Earth Mass: 333,000 * Earth Sun's luminosity - correct answer Equivalent to 4 * 10^24 100 Watt light bulbs Solar system's mass and the sun - correct answer 99.99% of all the mass of the solar system is in the Sun alone How long has the sun been shining for? - correct answer Sun has been shining for 4.5 billion years, and will continue for about another 5.5 billion years Sun and sunspots - correct answer Sunspots are 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 - correct answer A 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 - correct answer Two protons collide at very high speed, and stick together; one of them changes into a neutron; ends with a Deuterium nucleus (2H : 1 proton and 1 neutron, bound together), plus released energy