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
Length
Enter Part of Title
Display #
5
10
15
20
25
30
50
100
All
Is the Sun always up for exactly 12 hours at the equator?
(Beginner)
Why doesn't the length of each day change much around the solstices?
(Intermediate)
Share This Page
Share This
Random Question
What kind of interference must astronomers contend with when observing? (Beginner)
Most Recent
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 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
How can I find the star I have "bought"? (Beginner)
How do you measure the distance between Earth and the Sun? (Intermediate)
How do the astronauts communicate in space if sound cannot travel in a vacuum? (Beginner)
How do we know the mass of the Earth and the Moon? (Advanced)
Where did the Universe come from? (Intermediate)
Why are there both high and low tides? (Intermediate)
Why do planets not twinkle? (Intermediate)
The Moon slows the Earth's rotation, but how fast was it spinning billions of years ago? (Intermediate)
Which way does the sun travel in the southern hemisphere? (Beginner)
Did astronauts really go to the Moon, or is it a hoax? (Beginner)
What color is each planet? (Intermediate)
How do you measure the distance between Earth and the Sun? (Intermediate)
When was the last time all of the planets were aligned? (Beginner)
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)
What is the difference between a "star" and a "sun"? (Beginner)
How far is each planet from Earth? (Intermediate)
Why do airplanes take longer to fly West than East? (Intermediate)
Why are the Moon and Sun sometimes orange or red? (Beginner)
How does the location of sunrise and sunset change throughout the year? (Advanced)
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 do you measure the distance between Earth and the Sun? (Intermediate)
At what speed does the Earth move around the Sun? (Beginner)
How far is each planet from Earth? (Intermediate)
How are light and heavy elements formed? (Advanced)
How does the location of sunrise and sunset change throughout the year? (Advanced)
What is the difference between a "star" and a "sun"? (Beginner)
Why do airplanes take longer to fly West than East? (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)
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)
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