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!What calculations go into predicting eclipses?
(Advanced)
Can two lunar eclipses occur in the same month?
(Advanced)
Can we look back in time and see our galaxy forming?
(Intermediate)
Can we make a movie of the Milky Way galaxy's rotation?
(Beginner)
Can you tell time by the Big Dipper?
(Beginner)
Could someone travel the universe in his or her own lifetime?
(Beginner)
Could we be seeing dead stars?
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Did time go slower just after the Big Bang?
(Advanced)
Do we have to worry about relativity when studying galactic objects?
(Intermediate)
Do we really observe the edges of galaxies at different epochs?
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(Intermediate)
How can I watch the Perseid meteor shower?
(Beginner)
How do I maximize my chances of seeing shooting stars?
(Intermediate)
How do sunrise and sunset times change with altitude?
(Intermediate)
How is the time of sunrise calculated?
(Intermediate)
How long does it take for the Sun's light to reach us?
(Beginner)
If clocks run slow in a gravitational field, how can we know the true age of the Solar System and Universe?
(Intermediate)
If Mars is only about 35-60 million miles away at close approach, why does it take 6-8 months to get there?
(Intermediate)
If the Earth's rotation period is less than 24 hours, why don't our clocks fall out of sync with the Sun?
(Intermediate)
If the Universe was infinitely dense at the Big Bang, why didn't time stand still?
(Beginner)
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What is the universe expanding into? (Intermediate)
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What color is each planet? (Intermediate)
How are light and heavy elements formed? (Advanced)
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What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
Does the Sun orbit the Earth as well as the Earth orbiting the Sun? (Beginner)
How is it proved that the Universe is expanding? (Intermediate)
What is the evidence supporting the nebula theory of Solar System formation? (Intermediate)
What is the difference between a "star" and a "sun"? (Beginner)
Can artificial gravity be created in space? (Intermediate)
What color is each planet? (Intermediate)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
How are light and heavy elements formed? (Advanced)
How far is each planet from Earth? (Intermediate)
Are aliens or UFOs real? (Beginner)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
How does the location of sunrise and sunset change throughout the year? (Advanced)
Why do the planets orbit the sun? (Beginner)
What is the difference between a "star" and a "sun"? (Beginner)
When was the last time all of the planets were aligned? (Beginner)
What color is each planet? (Intermediate)
How are light and heavy elements formed? (Advanced)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
How far is each planet from Earth? (Intermediate)
What is the difference between a "star" and a "sun"? (Beginner)
How is it proved that the Universe is expanding? (Intermediate)
How does the location of sunrise and sunset change throughout the year? (Advanced)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
When was the last time all of the planets were aligned? (Beginner)
Can artificial gravity be created in space? (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)
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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