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Do unmanned spacecraft like Voyager travel in straight lines?
(Intermediate)
When unmanned spacecraft accelerate in space, what causes them to slow down?
(Intermediate)
Why did the Pioneer and Voyager take only 2 years to reach Jupiter, while Galileo and Cassini took more than 5 years?
(Intermediate)
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How do the astronauts communicate in space if sound cannot travel in a vacuum? (Beginner)
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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)
Editor's Pick
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)
Can artificial gravity be created in space? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
How are light and heavy elements formed? (Advanced)
Why do airplanes take longer to fly West than East? (Intermediate)
Is the distance from the Earth to the Sun changing? (Advanced)
When was the last time all of the planets were aligned? (Beginner)
Why can't a plane fly slowly and let the Earth pass underneath? (Beginner)
Is the Moon moving away from the Earth? When was this discovered? (Intermediate)
What color is each planet? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
How are light and heavy elements formed? (Advanced)
Can artificial gravity be created in space? (Intermediate)
Why do the planets orbit the sun? (Beginner)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
Why do airplanes take longer to fly West than East? (Intermediate)
How far is each planet from Earth? (Intermediate)
What is the universe expanding into? (Intermediate)
How are light and heavy elements formed? (Advanced)
What color is each planet? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
Can artificial gravity be created in space? (Intermediate)
Why do the planets orbit the sun? (Beginner)
How far is each planet from Earth? (Intermediate)
How do you measure the distance between Earth and the Sun? (Intermediate)
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)
What is the difference between a "star" and a "sun"? (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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Physics
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The Theory of Relativity
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The History of Astronomy
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