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Is light blueshifted when it is gravitationally lensed?
(Intermediate)
What would the Big Crunch look like to an observer on Earth?
(Advanced)
Why are there blue shifted galaxies?
(Intermediate)
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Why are stars and planets round? (Beginner)
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Is speed of light the same everywhere ? (Beginner)
How does Venus have sulphuric acid in it's clouds? (Beginner)
Earth's Bow Shock (Advanced)
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)
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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How did a transit of Venus provide astronomers with the first measurement of the Earth-Sun distance? (Intermediate)
How hot is each one of the layers of the sun? (Beginner)
How do we know what other planets (and stars, galaxies, etc.) are made of? (Intermediate)
How many stars are there in our Galaxy (Milky Way)? (Intermediate)
Will the Sun become a black hole one day? (Beginner)
Will we get sucked into the black hole at the center of the Milky Way? (Beginner)
Why are stars and planets round? (Beginner)
How does the parachute in a model rocket work? (Advanced)
Does the Milky Way spin counter-clockwise? If so, do all spiral galaxies spin in this direction and why? (Beginner)
How was the starting point for the Julian Date system chosen? (Advanced)
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)
How does the position of Moonrise and Moonset change? (Intermediate)
Why do we not have eclipses every month? (Beginner)
Why is the moon in a different place every night? (Beginner)
Why do the planets orbit the sun? (Beginner)
Which planet is most similar to Earth? (Intermediate)
What was the bright, smoothly moving star that I saw? (Beginner)
What are constellations used for? (Intermediate)
How long could life on Earth survive if the Sun stopped shining? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
How big is the Hubble Ultra Deep Field image? (Intermediate)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
Which planet is most similar to Earth? (Intermediate)
What are constellations used for? (Intermediate)
Why do the planets orbit the sun? (Beginner)
How does the position of Moonrise and Moonset change? (Intermediate)
Why do we not have eclipses every month? (Beginner)
How long could life on Earth survive if the Sun stopped shining? (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)
How do you measure the distance between Earth and the Sun? (Intermediate)
Is the Moon moving away from the Earth? When was this discovered? (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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SETI & Extraterrestrial Life
Physics
General Physics
The Theory of Relativity
People & Astronomy
Careers in Astronomy
Space Exploration & Astronauts
The History of Astronomy
Astronomy in the Arts