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Can "tired light theory" explain the observed redshifts of galaxies?
(Intermediate)
Can gravitational lensing from intervening galaxies cause the observed ripples in the Cosmic Microwave Background?
(Advanced)
Can we look back far enough in time to see the Big Bang?
(Beginner)
Could photons be dark matter?
(Intermediate)
Could the Universe have expanded faster than the speed of light at the Big Bang?
(Intermediate)
How big is the Universe?
(Intermediate)
How do we know the age of the Universe and the Earth?
(Intermediate)
What makes up most of the Universe?
(Beginner)
What's the difference between dark matter and dark energy?
(Intermediate)
Where, in relation to the entire universe, is the Milky Way located?
(Intermediate)
Why is the Cosmic Microwave Background not absorbed by interstellar hydrogen?
(Advanced)
Why is the WMAP picture of the CMB an ellipse?
(Intermediate)
Wouldn't the Big Bang theory be considered a hypothesis and not a theory?
(Intermediate)
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Why is our solar system so different from all the others we've found? (Intermediate)
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If I were hypothetically wearing a spacesuit and sitting on one of the Voyager space probes at their current positions in space, how much light would I have? (Intermediate)
What makes certain lunar eclipses so special? (Beginner)
Why is Earth's core molten? (Intermediate)
What will happen to Earth's tides as the moon moves away from us? (Intermediate)
How can spiral galaxies keep their shape? (Advanced)
Does a black hole have a "surface"? (Intermediate)
How can you link telescopes to make a bigger "effective telescope"? (Intermediate)
What should I know about the upcoming Solar Eclipse (2017)? (Beginner)
Do galaxies that are receding from us faster than the speed of light disappear from our observations? (Intermediate)
Why are astronomers interested in gravitational waves? (Intermediate)
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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 color is each planet? (Intermediate)
How far is each planet from Earth? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
Why can't a plane fly slowly and let the Earth pass underneath? (Beginner)
What is the difference between a "star" and a "sun"? (Beginner)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
Is the Moon moving away from the Earth? When was this discovered? (Intermediate)
What are the names of the earth, moon, sun, and solar system? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
What color is each planet? (Intermediate)
How far is each planet from Earth? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
Why can't a plane fly slowly and let the Earth pass underneath? (Beginner)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
Why are the Moon and Sun sometimes orange or red? (Beginner)
What is the difference between a "star" and a "sun"? (Beginner)
Why do the planets orbit the sun? (Beginner)
What would happen if an asteroid 10 kilometers across hit the Earth? (Beginner)
What color is each planet? (Intermediate)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
How far is each planet from Earth? (Intermediate)
If gravity isn't a force, how does it accelerate objects? (Advanced)
Why can't a plane fly slowly and let the Earth pass underneath? (Beginner)
What would happen if an asteroid 10 kilometers across hit the Earth? (Beginner)
What is the difference between a "star" and a "sun"? (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)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (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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