About Us
For Teachers
Most Popular
Most Recent
Astronomy Links
Image Credits
Cornell Astronomy
Ask a Question
Home
Our Solar System
The Earth
The Moon
The Sun
Planets & Dwarf Planets
Comets, Meteors, & Asteroids
The Universe
Extrasolar Planets
Stars & Star Clusters
Supernovae
Black Holes & Quasars
The Milky Way
Galaxies
Cosmology & the Big Bang
Observational Astronomy
Stargazing
Telescopes
Lunar & Solar Eclipses
Timekeeping
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
Spacetime
Enter Part of Title
Display #
5
10
15
20
25
30
50
100
All
Can you see the future as you fall into a black hole?
(Intermediate)
How can the Universe expand faster than the speed of light during inflation?
(Advanced)
How do gravitons escape black holes to tell the universe about their gravity?
(Advanced)
If gravity is a "curvature of space" rather than a force, why do a ball and bullet follow different paths?
(Intermediate)
If gravity isn't a force, how does it accelerate objects?
(Advanced)
If light has no mass, then what draws it into a black hole?
(Intermediate)
If spacetime is curved, is it possible for us to look into space and see light from Earth from long ago?
(Intermediate)
Is there any possibility that the Solar System or the Universe is in a black hole?
(Intermediate)
What are "curled" dimensions?
(Advanced)
What happens to spacetime inside a black hole?
(Intermediate)
What is a wormhole?
(Intermediate)
What would an "open geometry" for the universe look like?
(Advanced)
Why is the Universe flat and not spherical?
(Advanced)
Random Question
How can I measure the distance of a star? (Beginner)
Most Recent
If I were hypothetically wearing a spacesuit and sitting on one of the Voyager space probes at their current positions in space, how much light would I have? (Intermediate)
What makes certain lunar eclipses so special? (Beginner)
Why is Earth's core molten? (Intermediate)
What will happen to Earth's tides as the moon moves away from us? (Intermediate)
How can spiral galaxies keep their shape? (Advanced)
Does a black hole have a "surface"? (Intermediate)
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)
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)
Most Popular
Today
This Week
This Month
All Time
What color is each planet? (Intermediate)
How far is each planet from Earth? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
Why can't a plane fly slowly and let the Earth pass underneath? (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)
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)
How do you measure the distance between Earth and the Sun? (Intermediate)
What color is each planet? (Intermediate)
How far is each planet from Earth? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
Why can't a plane fly slowly and let the Earth pass underneath? (Beginner)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (Beginner)
Why are the Moon and Sun sometimes orange or red? (Beginner)
What is the difference between a "star" and a "sun"? (Beginner)
Why do the planets orbit the sun? (Beginner)
What would happen if an asteroid 10 kilometers across hit the Earth? (Beginner)
What color is each planet? (Intermediate)
Are there telescopes that can see the flag and lunar rover on the Moon? (Beginner)
How far is each planet from Earth? (Intermediate)
If gravity isn't a force, how does it accelerate objects? (Advanced)
Why can't a plane fly slowly and let the Earth pass underneath? (Beginner)
What would happen if an asteroid 10 kilometers across hit the Earth? (Beginner)
What is the difference between a "star" and a "sun"? (Beginner)
At what speed does the Earth move around the Sun? (Beginner)
Is the Moon moving away from the Earth? When was this discovered? (Intermediate)
What is the significance of the Tropic of Cancer, Tropic of Capricorn, Arctic Circle and Antarctic Circle? (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)
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)
Our Reddit AMAs
AMA = Ask Me (Us) Anything
June 2014 AMA
July 2013 AMA
Q&A Categories
Home
Our Solar System
The Earth
The Moon
The Sun
Planets & Dwarf Planets
Comets, Meteors, & Asteroids
The Universe
Extrasolar Planets
Stars & Star Clusters
Supernovae
Black Holes & Quasars
The Milky Way
Galaxies
Cosmology & the Big Bang
Observational Astronomy
Stargazing
Telescopes
Lunar & Solar Eclipses
Timekeeping
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