Astro 1 - Exam 3 | 100 Questions with 100% Correct Answers | Updated | Download to score A+

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what is the sun comprised of? - ✔✔73% hydrogen 25% helium why is the sun stable? - ✔✔outward force of gas pressure; inward force of gravity Where does the gas pressure in the sun come from? ... - ✔✔nuclear fusion reactions in the core at temperatures of 15 million degrees What is the diameter of the sun compared to earth? mass? luminosity (compared to 100W lightbulbs? - ✔✔diameter-109x; mass-333,000; luminosity- 4 x 10^24 What percent of mass in the solar system comes from the sun? - ✔✔99.9% how long has the sun been shining? how much longer will it shine? - ✔✔4.5 billion years; 5.5 billion years what are sunspots? - ✔✔slightly cooler regions on the sun's surface what causes sunspots? how long are their cycles? - ✔✔magnetic activity preventing hot material from rising to that region. they have 11 year cycles [Show More]

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