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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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Can you use an infinite line of reflectors to send light to the edge of the Universe? (Intermediate)
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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)
Can two galaxies move away from each other faster than the speed of light? (Intermediate)
What is a graviton? (Intermediate)
Why are there high tides during a Full Moon? (Intermediate)
Why is Neptune still considered a planet when Pluto crosses its orbit? (Intermediate)
Could there be objects orbiting interior to Mercury? (Intermediate)
Have the inner planets cleared their neighborhood? (Intermediate)
What caused the Big Bang and created the Universe? (Beginner)
If spacetime is curved, is it possible for us to look into space and see light from Earth from long ago? (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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How do rockets move in space? (Beginner)
How can I find the star I have "bought"? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
How do the astronauts communicate in space if sound cannot travel in a vacuum? (Beginner)
How do we know the mass of the Earth and the Moon? (Advanced)
What are RA and DEC? (Intermediate)
Where did the Universe come from? (Intermediate)
Why are there both high and low tides? (Intermediate)
Why do planets not twinkle? (Intermediate)
The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (Intermediate)
What color is each planet? (Intermediate)
How do you measure the distance between Earth and the Sun? (Intermediate)
When was the last time all of the planets were aligned? (Beginner)
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)
What is the difference between a "star" and a "sun"? (Beginner)
How far is each planet from Earth? (Intermediate)
Why do airplanes take longer to fly West than East? (Intermediate)
Why are the Moon and Sun sometimes orange or red? (Beginner)
How does the location of sunrise and sunset change throughout the year? (Advanced)
What color is each planet? (Intermediate)
When was the last time all of the planets were aligned? (Beginner)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
How far is each planet from Earth? (Intermediate)
How are light and heavy elements formed? (Advanced)
How does the location of sunrise and sunset change throughout the year? (Advanced)
What is the difference between a "star" and a "sun"? (Beginner)
Why do airplanes take longer to fly West than East? (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)
How long does it take for the Sun's light to reach us? (Beginner)
What is the universe expanding into? (Intermediate)
When will Halley's Comet return? (Intermediate)
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