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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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How do distant galaxies differ from those nearby? (Advanced)
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Is speed of light the same everywhere ? (Beginner)
How does Venus have sulphuric acid in it's clouds? (Beginner)
Earth's Bow Shock (Advanced)
How much does the Earth "wobble" on its orbit due to the Moon's gravity? (Intermediate)
Why is the sun red? During sunset, Northeastern US, Summer 2021 (Beginner)
Why do rays from Sun appear to converge at a point? (Beginner)
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)
How do we know what we observe is x light years away? (Beginner)
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What is the universe expanding into? (Intermediate)
What do I need to do to become an astronomer? (Beginner)
What's the difference between astronomy and astrology? (Beginner)
Why is looking out into space the same as looking back in time? (Beginner)
Can we find the place where the Big Bang happened? (Intermediate)
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What is the three-body problem? (Advanced)
What would happen if an asteroid 10 kilometers across hit the Earth? (Beginner)
At what speed does the Earth move around the Sun? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
How long could life on Earth survive if the Sun stopped shining? (Beginner)
How is the Cepheid yardstick validated? (Advanced)
If gravity isn't a force, how does it accelerate objects? (Advanced)
How does the position of Moonrise and Moonset change? (Intermediate)
What is the difference between a "star" and a "sun"? (Beginner)
How can we see the Milky Way if we are inside it? (Intermediate)
What would happen if an asteroid 10 kilometers across hit the Earth? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
How can we see the Milky Way if we are inside it? (Intermediate)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
How does the position of Moonrise and Moonset change? (Intermediate)
How long could life on Earth survive if the Sun stopped shining? (Beginner)
But seriously: what was there before the Big Bang? (Beginner)
What is the difference between a "star" and a "sun"? (Beginner)
Why do the planets orbit the sun? (Beginner)
Is speed of light the same everywhere ? (Beginner)
What would happen if an asteroid 10 kilometers across hit the Earth? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
How can we see the Milky Way if we are inside it? (Intermediate)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
How long could life on Earth survive if the Sun stopped shining? (Beginner)
What is the difference between a "star" and a "sun"? (Beginner)
Why do the planets orbit the sun? (Beginner)
At what speed does the Earth move around the Sun? (Beginner)
How does the position of Moonrise and Moonset change? (Intermediate)
Why are there high tides during a Full Moon? (Intermediate)
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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