Space

Why does the moon look so much bigger when it is near the horizon than when it is high up in the sky? This question has been pondered for hundreds if not thousands of years, and is commonly referred to as the moon illusion.

A space shuttle launch is expensive -- about $10,000 per pound. The LiftPort Group is developing a new system that could cut the cost down to about $400 per pound. Find out how a space elevator might be your ticket into orbit.

By Kevin Bonsor

Where I live it is pretty common to see "shooting stars" -- streaks of light in the sky at night. How big is a shooting star? Do they land on earth or do they burn up? Do they land on the ground as meteorites?

What is a solar sail? How can you use sunlight to move a spacecraft in outer space? In this article, HowStuffWorks will show you how solar sail technology works, take an in-depth look at the Cosmos-1 mission and find out what solar-sails mean for future space travel.

By Kevin Bonsor

The sun warms our planet every day, provides the light by which we see and is necessary for life on Earth. But what is it exactly, and what will happen when it burns itself out?

By Julia Layton & Craig Freudenrich, Ph.D.

When you look up at night and see thousands of stars, have you ever wondered what you are looking at? Learn what stars are and how they live and die!

By Craig Freudenrich, Ph.D.

The Chandler wobble is the change in the spin of Earth on its axis. Think of the wobble you see in a toy top when it first starts spinning or slows down. Its 'poles' do not spin in a perfectly straight line.

At a drag race, I once saw a rocket car that was supposedly powered by spraying hydrogen peroxide on a silver mesh. The resultant reaction produced huge amounts of pure white smoke and apparently enough thrust to propel the car rapidly down the track. Does hydrogen peroxide really react with silver that way?

Apollo astronauts left a lot of stuff behind on the moon. Can you see any of that from Earth, even with a telescope?

By Valerie Stimac & Sascha Bos

If "nature abhors a vacuum," then why doesn't the vacuum of space suck away all of the Earth's atmosphere?

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.

In science, we are learning about the atmosphere. It protects us from meteors because it burns them up. So, why doesn't the space shuttle burn up?

Can the curvature of the Earth only be seen from outer space? If you didn't know that the Earth is a sphere, there are three common observations you could use to convince yourself that it is.

Believe it or not, the hardest part of space exploration is getting a spaceship off the ground. Explore the basics of propulsion and learn about both solid-fuel and liquid-fuel rocket engines.

By Marshall Brain

Less than 100 miles from Las Vegas, is the most famous secret military installation on the planet: Area 51. For decades, the U.S. government refused to acknowledge it existed. But now, the secret is out.

By Jonathan Strickland & Patrick J. Kiger

The hunt for exoplanets, planets orbiting sun-like stars, is on! Thanks to new equipment, NASA has spotted thousands of them. But which ones might be able to handle life?

By William Harris & Jacob Silverman

Using current rocket engine technology, a trip to Mars takes seven months. Fusion propulsion would cut that trip in half. Find out what fusion is and how it could speed up space travel.

By Kevin Bonsor

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!

As the International Space Station astronauts return to Earth after a three-month stay, learn about the effects of weightlessness on the body.

By Craig Freudenrich, Ph.D.

The Voyager spacecraft use 23-watt radios. This is higher than the 3 watts a typical cell phone uses, but in the grand scheme of things it is still a low-power transmitter. The key to receiving the signals is therefore not the power of the radio, but a combination of three other things.

If I was on the moon and the earth was black (no lights were on) and a flashlight was turned on facing the moon, would I see the light? If I couldn't, would there be any way to detect any residual matter that came from the light on Earth or does light die after a certain distance?

Thousands of satellites fly overhead every day, helping us with things like weather forecasts, scientific research, communications, TV broadcasts (and maybe some surreptitious spying). How much do you know about these eyes in the sky?

By Gary Brown & William Harris

Of course we want to go to Mars. Until we figure it out though, roving robots with names like Spirit, Opportunity, Sojourner and Curiosity are our best bet for digging up dirt on our nearest planetary neighbor. Want to go along for the ride?

By Marshall Brain & Kate Kershner

Jupiter is the largest planet in the solar system. Big as this gas giant is though, next to the sun, it's still small.

By Mark Mancini

Mercury is the closest planet to the sun, and it's the smallest in the solar system. So why does it have longer days than we have on Earth?

By Mark Mancini