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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 many constellations are there? (Beginner)
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How much does the Earth "wobble" on its orbit due to the Moon's gravity? (Intermediate)
Why is the sun red? During sunset, Northeastern US, Summer 2021 (Beginner)
Why do rays from Sun appear to converge at a point? (Beginner)
But seriously: what was there before the Big Bang? (Beginner)
How far can photons move freely in the early universe (Advanced)
How likely is it that the Solar System has had or will have a close encounter with another star? (Intermediate)
How do we know what we observe is x light years away? (Beginner)
What makes quantum mechanics and general relativity incompatible? (Advanced)
What are we doing about Space Junk?
What what a black hole merger look like from a telescope? (Advanced)
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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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Does the temperature of matter increase as it is accelerated to relativistic speeds? (Advanced)
What is the difference between a "star" and a "sun"? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
Why are there active volcanos on Io? (Intermediate)
What do "homogeneity" and "isotropy" mean? (Intermediate)
How far is each planet from Earth? (Intermediate)
Why do the planets orbit the sun? (Beginner)
Do constellations looks the same from space? (Beginner)
Could someone travel the universe in his or her own lifetime? (Beginner)
Can you use an infinite line of reflectors to send light to the edge of the Universe? (Intermediate)
Is the Moon moving away from the Earth? When was this discovered? (Intermediate)
Why is the moon in a different place every night? (Beginner)
How does the position of Moonrise and Moonset change? (Intermediate)
What is the difference between a "star" and a "sun"? (Beginner)
Why do the planets orbit the sun? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
How are light and heavy elements formed? (Advanced)
At what speed does the Earth move around the Sun? (Beginner)
How long could life on Earth survive if the Sun stopped shining? (Beginner)
What is the evidence supporting the nebula theory of Solar System formation? (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)
How does the position of Moonrise and Moonset change? (Intermediate)
How do you measure the distance between Earth and the Sun? (Intermediate)
Why do the planets orbit the sun? (Beginner)
At what speed does the Earth move around the Sun? (Beginner)
How long could life on Earth survive if the Sun stopped shining? (Beginner)
Why is the moon in a different place every night? (Beginner)
How are light and heavy elements formed? (Advanced)
How can we see the Milky Way if we are inside it? (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)
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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