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The first stars formed in the Universe were composed of 90% hydrogen, 10% helium, and very little else.
Q20: The black hole at the center of
Q29: Astronomers refer to the dark center of
Q33: Stars are born from the interstellar medium,
Q38: The vertical axis (Y-axis) of the Hertzsprung-Russell
Q47: All type I supernovae are caused by
Q47: The _ is a high temperature, low
Q48: Explain the steps involved in clearing a
Q49: Explain the reasoning that leads astronomers to
Q49: What is the unified model of active
Q50: What is the safest way to view