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- 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)
- What caused the Big Bang and created the Universe? (Beginner)
- If spacetime is curved, is it possible for us to look into space and see light from Earth from long ago? (Intermediate)
Editor's Pick
- What should I know about the upcoming Solar Eclipse? (2017)
- 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)
Most Popular
- What color is each planet? (Intermediate)
- 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)
- How do you measure the distance between Earth and the Sun? (Intermediate)
- At what speed does the Earth move around the Sun? (Beginner)
- How are light and heavy elements formed? (Advanced)
- How does the position of Moonrise and Moonset change? (Intermediate)
- What is the difference between a "star" and a "sun"? (Beginner)
- Why are the Moon and Sun sometimes orange or red? (Beginner)
- Why do the planets orbit the sun? (Beginner)
- Why are the Moon and Sun sometimes orange or red? (Beginner)
- 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 far is each planet from Earth? (Intermediate)
- How do you measure the distance between Earth and the Sun? (Intermediate)
- At what speed does the Earth move around the Sun? (Beginner)
- What is the difference between a "star" and a "sun"? (Beginner)
- Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
- How are light and heavy elements formed? (Advanced)
- When was the last time all of the planets were aligned? (Beginner)
- Why are the Moon and Sun sometimes orange or red? (Beginner)
- What color is each planet? (Intermediate)
- When was the last time all of the planets were aligned? (Beginner)
- 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)
- How do you measure the distance between Earth and the Sun? (Intermediate)
- At what speed does the Earth move around the Sun? (Beginner)
- What is the difference between a "star" and a "sun"? (Beginner)
- How does the position of Moonrise and Moonset change? (Intermediate)
- Why do the planets orbit 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)
- How long does it take for the Sun's light to reach us? (Beginner)
- What is the universe expanding into? (Intermediate)
- When will Halley's Comet return? (Intermediate)
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