HOW ON EARTH

6 Severe Weather Terms to Know Ahead of Spring Storms

Knowing the difference between these common terms can bolster your safety in severe weather.

8 of the Biggest Tsunamis in History

The biggest tsunami ever recorded reached 1720 feet high—which is taller than the Willis Tower in Chicago.

Blow Hard: 11 of the Biggest Volcanic Eruptions of All Time

Volcanoes do more than just spew lava. They can usher in revolutions, inspire great works of literature, or even convince people they're seeing ghosts.

Mauna Loa erupts in Hawaii. A hypothetical eruption of the Yellowstone supervolcano would be thousands of times larger.

What is a Supervolcano?

What distinguishes this kind of volcano from regular volcanoes, and what will happen if—or when—one erupts?

Megafauna like woolly mammoths dominated during the ice age.

20 Cool Facts About the Ice Age

From what causes ice ages and how many we’ve had, to the species that thrived and the ones that died, here’s what you need to know.

Category 4 Hurricane Harvey decimated Houston in 2017.

How Are Hurricane Categories Determined?

In order to assign a numeric category value to a hurricane, meteorologists look to the Saffir-Simpson Hurricane Wind Scale.

It's not even close to being this glamorous.

How Do Oysters Make Pearls?

It sometimes starts with a grain of sand—but not always.

15 Amazing Facts About "The Year Without a Summer"

Few volcanoes had had such a dramatic and devastating impact on the world as Indonesia's Mount Tambora.

16 Towering Facts About Mount Everest

Mount Everest is the tallest and highest peak on Earth. Or is it? Here’s everything you need to know about the world’s most famous mountain.

Mount Saint Helens erupts May 18, 1980 in Washington State. The natural occurrence blew a mushroom cloud of ash thousands of miles into the air.

11 Explosive Facts About Mount St. Helens

When it blew on May 18, 1980, Mount St. Helens became the most explosive volcanic eruption in U.S. history. And no, it’s not done.

A circumhorizontal arc, or "fire rainbow," in Japan.

What Causes a Rainbow If There Isn’t Any Rain?

As the saying goes, you can’t have a rainbow without a little rain. But you can have parhelia and circumhorizontal arcs.

An image of Earth from 1 million miles away snapped on July 6, 2015 by a camera on NASA's Deep Space Climate Observatory spacecraft.

100 Facts About Earth

How much do you know about the blue marble we call home? From how our planet formed to just how many species there are, here are 100 things you need to know about Earth.

Two people can, however, look at the same photo of a rainbow.

Rainbow Disconnection: Why No Two People Can Ever See the Same Rainbow

How do rainbows form? It’s all about light waves, water, and angles—and that includes the angle from which you see one.

Calving is one way that glaciers lose ice.

12 Disappearing Glaciers Around the World

If you want to behold some of the world's most majestic glaciers on six continents, you better act fast.

Lenticular clouds in Cape Town, South Africa.

8 Strange Cloud Types and What They Mean

The next time somebody points out a UFO-shaped cloud, you can whip out the word ‘lenticular.’ They’ll love it.

Deep-sea urchins are seen in an ocean trench near New Zealand.

8 Surprising Facts About the Deepest Part of the Ocean

Just a handful of people have ever been to the deepest part of the ocean, but what we've learned about life in the hadal zone is astonishing.

The small torn of Peshtigo, Wisconsin, before being destroyed by fire.

The Great Peshtigo Fire: The Deadliest Blaze in American History

On October 8, 1871—the same day the Great Chicago Fire killed 300—a far deadlier wildfire swept across Wisconsin.