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A light year is a way of measuring distance. That doesn't make much sense because "light year" contains the word "year," which is normally a unit of time. Even so, light years measure distance.

Have you ever really thought about the scale of the universe? A good starting point is the teaspoon.

If you took all of the matter in the universe and you pushed it all into one corner, how much space would it take up? I am trying to understand how much of the universe is 'empty.'

It turns out that measuring the distance to a star is an interesting problem! Astronomers have come up with two different techniques to estimate how far away any given star is.

There are all kinds of telescopes, but you can make a simple one on your own. You'll need a few basic supplies and this step-by-step article. Get ready to star-gaze!

Astronomers may no longer use cosmic measurements to predict the future, but they do use telescopes to explore unknown regions of the heavens. What are the best telescopes out there?

If your idea of photographing the stars has nothing to do with Hollywood, you might be interested in astrophotography -- the sky's literally the limit.

Astronauts have a reputation for being the brave and skilled few willing to risk their lives by strapping themselves aboard a rocket and blasting into outer space. How much do you know about them?

Astronauts risk their lives in the pursuit of science. How does NASA know who can be an astronaut? And what do they do when they're not in space?

Space food has come a long way from Project Mercury's paste-filled tubes. Today's astronauts select menus that include everything from macaroni and cheese to brownies. So do astronauts really eat space ice cream?

We are seeing a lot more space suits now that the international space station is occupied. Learn how space suits work and why they cost $12 million each!

In its nearly 30-year history, the space shuttle program has seen exhilarating highs and devastating lows. Learn all about the space shuttle program.

Imagine waking up in the morning, looking out your window and seeing the planet Earth below you. What would it be like to live in space? Find out all about the International Space Station.

When most people think of NASA, they think of astronauts and Kennedy Space Center, but there's much more to this nearly 50-year-old organization. Learn about the history of NASA, how its structured and exactly what it does.

Since its inception in the late '50s, NASA has accomplished some amazing technical feats. But what are some of the administration's greatest moments?

Although most people today will never set foot on the moon, it's likely you come into contact with a NASA byproduct every day.

Explore the historic space voyages, technology and people that have shaped 50 years of NASA.

The Voyager space probes took dazzling pictures of planets no one had ever seen. And they're still on the move, carrying golden records with a message for aliens -- complete with bagpipes and Louis Armstrong.

The second Mars Exploration mission rover, Opportunity, has successfully landed and is now sending back breathtaking photos. See what these high-tech rovers are all about.

People around the world watched as Neil Armstrong touched the moon and declared, "That's one small step for man; one giant leap for mankind." But how did we put a man on the moon?

Because an Earth-like environment is created within a spacesuit, it allows you to walk around in space in relative safety. But outer space is an extremely hostile place and could kill you if you aren't protected.

It was a small step for a man, a giant leap for mankind. But some people say that the moon landings never happened at all. Why all the conspiracy theories?

Blasting a spacecraft into space is one thing. Bringing it back in one piece is another. Spacecraft are likely to burn up into bits if they aren't specially insulated and designed for the ride.