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What are "blue stragglers" in globular clusters?
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What would happen if two stars collided?
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What month was it when Odysseus saw Orion in 1000BC? (Advanced)
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But seriously: what was there before the Big Bang? (Beginner)
How far can photons move freely in the early universe (Advanced)
How likely is it that the Solar System has had or will have a close encounter with another star? (Intermediate)
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What makes quantum mechanics and general relativity incompatible? (Advanced)
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What is the universe expanding into? (Intermediate)
What do I need to do to become an astronomer? (Beginner)
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How does the position of Moonrise and Moonset change? (Intermediate)
What is the difference between a "star" and a "sun"? (Beginner)
Why is the moon in a different place every night? (Beginner)
Why do we not have eclipses every month? (Beginner)
At what speed does the Earth move around the Sun? (Beginner)
What is the significance of the second focus of elliptical orbits of planets in our Solar System? (Intermediate)
How are light and heavy elements formed? (Advanced)
Why do the planets orbit the sun? (Beginner)
What is the evidence supporting the nebula theory of Solar System formation? (Intermediate)
Can artificial gravity be created in space? (Intermediate)
What is the difference between a "star" and a "sun"? (Beginner)
How does the position of Moonrise and Moonset change? (Intermediate)
How do you measure the distance between Earth and the Sun? (Intermediate)
Why do the planets orbit the sun? (Beginner)
But seriously: what was there before the Big Bang? (Beginner)
At what speed does the Earth move around the Sun? (Beginner)
How long could life on Earth survive if the Sun stopped shining? (Beginner)
How are light and heavy elements formed? (Advanced)
What is the universe expanding into? (Intermediate)
Why is the moon in a different place every night? (Beginner)
What is the difference between a "star" and a "sun"? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
Why do the planets orbit the sun? (Beginner)
How does the position of Moonrise and Moonset change? (Intermediate)
How long could life on Earth survive if the Sun stopped shining? (Beginner)
At what speed does the Earth move around the Sun? (Beginner)
Is the Moon moving away from the Earth? When was this discovered? (Intermediate)
But seriously: what was there before the Big Bang? (Beginner)
What is the universe expanding into? (Intermediate)
What was the bright, smoothly moving star that I saw? (Beginner)
What's going to happen on December 21st 2012? (Intermediate)
What color is each planet? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
How far is each planet from Earth? (Intermediate)
Is the Moon moving away from the Earth? When was this discovered? (Intermediate)
How do you measure the distance between Earth and the Sun? (Intermediate)
Why do the planets orbit the sun? (Beginner)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
When was the last time all of the planets were aligned? (Beginner)
How long does it take for the Sun's light to reach us? (Beginner)
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