Geophysics

We bet you're looking up the longest river in the U.S. to settle a bet: Is it the Missouri River or the Mississippi River? It depends how you measure.

By Marie Look

The smallest state in the U.S.A. isn't the same as the state with the lowest population. In fact, the five smallest by each measure are completely different.

By Yara Simón

Subsidence, or the decline in the elevation of land surface, is creating a problem for some coastal cities as sea levels rise.

By Jesslyn Shields

Each year, Earth sees two equinoxes and two solstices. But how much do you actually know about these events? Take the quiz and find out!

By Alia Hoyt

Water surrounds us, falling from the sky and pouring from faucets, and yet many of us never ask where it comes from. The answer stretches way back — before tides and thunderclouds to the big bang.

By Jonathan Atteberry & Ian O'Neill, Ph.D.

Do you ever play that game in which you select the items you'd bring if you got stuck on a desert island? Along with that treasured bootleg recording of your favorite band, we think that an endless supply of water should be at the top of your list. Here's why.

By Jonathan Atteberry

A common misconception is that magma comes from the Earth's molten core. It really comes from the mantle, the layer between the core and the crust. Will it ever run out?

By Tracy V. Wilson

Huge walls of cascading water never cease to capture our attention with their majesty. Ready to marvel at nature? Check out some of the most beautiful waterfalls in the world.

By Rick Mayda

Few Americans like the switching between Daylight Saving Time and Standard Time, but there's conflict on whether to switch permanently to DST or to ST. What are the pros and cons of permanent DST?

By Allison Troutner

It's possible that the giant, deadly serpent hanging out at the bottom of Fosse Dionne spring is just a legend, but divers have disappeared trying to find out, so who knows?

By Jesslyn Shields

Deep underneath Antarctica, there lies a hidden lake. Roughly the size of North America's Lake Ontario, the buried landmark has inspired curiosity and controversy for decades.

By Mark Mancini

Some say UFOs, while others say a meteor strike formed the Carolina Bays. Whatever created these isolated ponds and wetlands across North and South Carolina left a wondrous ecosystem that is in dire need of protection.

By Allison Troutner

Let's say you have a lunch date to make – and it's on the other side of the planet. Wouldn't it be convenient to pop down a hole through Earth's innards? But what would really happen if you did?

By Nicholas Gerbis

You probably know that the North Pole does not stay in the same spot. The North and South Poles can actually change positions. What causes this? Find out in this article.

By Tracy V. Wilson

A seismograph can accurately measure the movement of the Earth during a quake. How does a seismograph work, though, and what is the Richter scale that is associated with earthquakes? Learn the answers to these questions in this article.

By Sascha Bos

Water is one of the most abundant substances on the planet. About 70 percent of our planet is covered by oceans, but just how much water is there on Earth?

By HowStuffWorks.com Contributors & Yara Simón

Gravity is a force that we experience every minute of our lives, but hardly notice or give a passing thought to in our daily routines. Have you ever wondered what gravity is and how it works? Learn about the force of gravity in this article.

By Julia Layton & Austin Henderson

On a planet that is 70 percent water, people don't have enough clean, safe water to drink. We're in a water crisis, and water rights are becoming a big issue. What happens if we just plain run out?

By Josh Clark

In its purest form, it's odorless, nearly colorless and tasteless. It's in your body, the food you eat and the beverages you drink. All forms of life need it. What substance is more necessary to our existence than any other? Water.

By Shanna Freeman

Water is just hydrogen and oxygen, so why can't we do what nature does and combine the two? Unfortunately, it's not that simple, and the results can be rather ... explosive.

By Josh Clark & Jennifer Walker-Journey

Famine might bring to mind historical tragedies or modern media coverage of tiny children with swollen bellies. But how does the unimaginable -- a widespread loss of food -- actually happen?

By Jessika Toothman

It's not just the size that differentiates a lake from a pond. The real distinctions flow much deeper.

By Sharise Cunningham

You've probably heard of the Tropics of Cancer and Capricorn, but do you know the difference?

By Michelle Konstantinovsky

You've probably heard of the Tropics of Capricorn and Cancer, but do you know the difference?

By Michelle Konstantinovsky

The Arctic Circle is a region marked by frigid temperatures, strange sunlight and glaciers galore. And for hundreds of thousands of people, it's also home sweet home.

By Mark Mancini