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Can you use an infinite line of reflectors to send light to the edge of the Universe?
(Intermediate)
Could someone travel the universe in his or her own lifetime?
(Beginner)
How are photons created and destroyed?
(Advanced)
How do photons from distant objects maintain enough energy to reach us?
(Intermediate)
How do planets capture satellites?
(Advanced)
How do you calculate the lifetime of the Sun?
(Advanced)
How long do supernova remnants last?
(Intermediate)
How much power is contained in a beam of light?
(Intermediate)
How powerful are quasars?
(Intermediate)
Is cosmic expansion happening on microscopic scales?
(Advanced)
Is light of different colors affected differently by gravity?
(Intermediate)
What causes a particle to decay?
(Intermediate)
What is the photoelectric effect? Why can't multiple low-frequency photons free an electron?
(Intermediate)
What type of energy does a black hole have?
(Intermediate)
When the Sun converts mass to energy, do the orbits of the planets change?
(Advanced)
Where did the matter in the universe come from?
(Intermediate)
Where did the Universe come from?
(Intermediate)
Where does the kinetic energy of infalling bodies come from?
(Intermediate)
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Could someone travel the universe in his or her own lifetime? (Beginner)
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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)
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)
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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)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
What is the universe expanding into? (Intermediate)
Why do airplanes take longer to fly West than East? (Intermediate)
How far is each planet from Earth? (Intermediate)
What is the difference between a "star" and a "sun"? (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)
When was the last time all of the planets were aligned? (Beginner)
Why do the planets orbit the sun? (Beginner)
Which planets have rings? (Beginner)
What color is each planet? (Intermediate)
What is the difference between a "star" and a "sun"? (Beginner)
Why are the Moon and Sun sometimes orange or red? (Beginner)
How far is each planet from Earth? (Intermediate)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
Why do airplanes take longer to fly West than East? (Intermediate)
Can artificial gravity be created in space? (Intermediate)
How does the location of sunrise and sunset change throughout the year? (Advanced)
When was the last time all of the planets were aligned? (Beginner)
What color is each planet? (Intermediate)
Can a person go into a black hole and come out alive? (Beginner)
What is the difference between a "star" and a "sun"? (Beginner)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
Which planets have rings? (Beginner)
Can artificial gravity be created in space? (Intermediate)
How far is each planet from Earth? (Intermediate)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
Why do airplanes take longer to fly West than East? (Intermediate)
At what speed does the Earth move around the 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)
How long does it take for the Sun's light to reach us? (Beginner)
When was the last time all of the planets were aligned? (Beginner)
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