Geophysics

Researchers have been asking this question for almost a century and now we're a little closer to the answer. Something else to ponder: Every 27.5 million years there is usually a mass extinction.

By Valerie Stimac

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

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

By Sharise Cunningham

The Earth is split up into 24 time zones based on longitudinal lines. But those lines all converge at the North and South poles, so what's the time there?

By Mark Mancini

The autumnal equinox is the day Earth is perfectly angled to the sun, so the day and night are of equal length. Well, almost.

By Kathryn Whitbourne

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

The stratosphere is the second-lowest level in Earth's atmosphere. It's a bastion of ozone gas and rapid winds, where clouds are scarce, but life endures.

By Mark Mancini

Since its discovery in 1870, the Wyoming cone geyser Old Faithful has wowed spectators with its predictable eruptions, but its eruptions are not quite as predictable or prodigious as they once were.

By Mark Mancini

Ice volcanoes form when it's freezing cold outside and choppy water is forced to erupt through a hole in the ice around a body of water, cascading down into the classic shape of a volcano.

By Jesslyn Shields

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

The world has only had time zones since the late 1800s. Some people think we should eliminate them and have just one universal time instead.

By Patrick J. Kiger

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.

The spring, or vernal, equinox traditionally marks the first day of spring — but climate scientists use a different date altogether. Find out more about this and other facts about the spring equinox.

By Mark Mancini

The Ancient Earth visualization map shows the movement of the planet's tectonic plates in a really cool way.

By Patrick J. Kiger

Sastrugi are gorgeous snow formations found in the polar north, but they're also no fun to travel over.

By Jesslyn Shields

Prior to the mid-1990s, the magnetic north pole traveled at speeds of around 9 miles per year. Now, it's 34 miles annually. What accounts for the acceleration?

By Mark Mancini

Lakes seem like serene places to escape and enjoy peace and quiet. So you'd probably be surprised to learn that a lake can actually explode without warning. It's happened, with deadly consequences.

By Mark Mancini

Stratospheric Aerosol Injection (SAI) is a controversial possibility in the effort to slow the rate of climate change.

By Patrick J. Kiger

A bubbling mud pool is moving toward the San Andreas Fault, but scientists don't see evidence of an impending earthquake.

By Stell Simonton

The oceans' levels change daily across the globe. We know them as tidal changes. But what causes this constant shift in sea level and why is it more dramatic is some places than others?

By Mark Mancini

June 20 marks the summer solstice, the longest day of the year. Here are five cool facts about it.

By Mark Mancini