The South Pole is the most inhospitable place on Earth—yet, each year, around 50 brave scientists and staff endure the winter there. Outside temperatures approach minus 120 degrees Fahrenheit in constant darkness.

And they better hope nothing goes wrong. Because no one can come to help them.

The South Pole is 800 miles from the nearest human contact. That’s farther than the International Space Station, which orbits less than 400 miles above Earth.

From research bases on the Antarctic coast, it takes planes 5 to 8 hours to fly to the South Pole. But it’s so cold in winter that jet fuel turns to slush, meaning no flights can come or go.

An over-land caravan of snow tractors in the summer takes 40 days.

The sun is up in summer for more than 4,000 hours, one six-month-long day. At that time, the South Pole research station has its highest population, 200 scientists and staff. They study solar spots and atmospheric ozone, cosmic rays and neutrinos.

Low temperatures still average negative 20 degrees Fahrenheit.

In the fall, the sun nears the horizon for six weeks of dusk. Then it sets and is gone for three months for that seemingly endless night that is Antarctic winter.

It takes a special person to endure the isolation, darkness, danger and lethal cold.

Landslides happen when a slope becomes unstable—because of denuding, from a fire or deforestation; over-steepening, from erosion or mining; overloading, from a reservoir or heavy snowpack; or oversaturation, with rain or melt water.

So many things can cause a landslide that they happen in every U.S. state and nearly every country.

When the slope gives way, soil can speed downhill at 50 to 100 miles an hour, carrying trees, boulders, cars, even houses.

Earthquakes trigger just five percent of landslides. Twenty percent are caused by human activities, while three-quarters come from precipitation.

Though some landslides happen suddenly, most give warning signs: cracks in pavement or soil, earth bulging at the base of a slope, water springs in new places.

Your chances of getting caught in a slide are remote. But if you live in a landslide-prone area, keep these things in mind:

Risk comes from uphill. You may want to move bedrooms or living areas to the downhill side of the house.

If you suspect a slide is coming, open downhill windows and doors to allow debris that could pass through the house to exit.

To escape a landslide, go up! Upstairs, and up on top of furniture, to have the best chance to stay on top of the debris.

In the very unlikely event you’re trapped, never give up. Make noise so rescue teams can find you.

Herbivores eat plants, and carnivores eat animals that eat plants, to get their energy.

Plants and many bacteria create their own energy through photosynthesis, which depends on chlorophyll…which requires nitrogen.

As we’ve described in other episodes, most nitrogen on Earth is in the form of N2, the inert nitrogen gas that won’t bond with other compounds, making it useless to plants.

So, most plants rely on bacteria that cling to their roots and split the nitrogen in the soil for them. But when they can’t get enough, humans help them out, with nitrogen-rich fertilizers.

Early fertilizers relied on naturally concentrated nitrogen. For instance, bat colonies eat insects, which contain nitrogen, then excrete nitrogen-rich droppings. For centuries, humans harvested tons of bat guano to fertilize our crops.

But demand outstripped supply, so we had to invent a new source. At the start of the twentieth century, two German chemists devised a way to combine the nitrogen in air with hydrogen produced from natural gas to form ammonia, NH3. And their work won a Nobel prize…

Because liquid ammonia could then be used to mass produce nitrogen-rich fertilizers. This drove the massive expansion of industrial agriculture—which has both created and allowed us to feed a growing global population.

There’s an Irish saying, “There’s a pot of gold at the end of every rainbow.”

But it used to say, “you’re as likely to find a pot of gold as the end of the rainbow.”

That’s because if you go looking for its end, the rainbow vanishes.

Rainbows occur when water droplets—from rain, mist, waterfalls, even sea spray—hang in the air.

When sunlight enters the droplet, some will reflect off the back side and pass again out the front.

As sunlight passes twice through the water, the different wavelengths that make it up bend at different angles, which splits the entering white light into the spectrum of rainbow colors.

Your position, in relation to the sun and the water droplet, affects how much and which light reaches your eyes. Meaning, you determine how much rainbow you see.

If the sun is directly behind you, and low in the sky, the largest amount of light is reflected back toward you, and you’ll see a strong rainbow.

If the sun is 90 degrees to your right or left, you’ll see less reflected light and a weak rainbow.

If the sun is high in the sky or on the other side of the water droplets, no light reflects back to you, and you’ll see no rainbow.

This also means that, as you move, the amount of rainbow you see changes.

If you travel far enough toward what appears to be its end, the rainbow, and your pot of gold, will gradually disappear.

Tornadoes are mysterious. But on this EarthDate, we’ll try to unravel a few of their secrets.

You’ve probably heard there’s a “tornado season” that happens in “tornado alley.” Well, not exactly.

Tornadoes can happen almost anywhere—North and South America, Australia and New Zealand, South Africa, and the Indian subcontinent, where they’re most deadly due to higher population density.

And they can happen any time. Most occur within a few months…but that depends on where you are. In the southeastern US, it’s January through March. In the central plains, April through June. In the Midwest, July through September. The only months they’re less frequent are October through December.

Tornadoes appear to form from the cloud downward. But that’s not really the case. Researchers think most of them form horizontally, within the cloud, like a rolling barrel. Then an updraft turns them vertical, and they extend to the ground…

Or not. Some scientists think they may form from the bottom up, as a swirling wind eddy on the ground reaches up to the cloud, connecting to and triggering that rolling barrel of wind. Or it could be some of each.

But we can’t really tell by looking at radar since tornadoes form too quickly and too near the ground for our current technology to map them.

Clearly, there’s still a lot of mystery surrounding tornadoes. But as research comes in, we’ll keep blowing it your way.

In the 1800s, scientists found a 400-million-year-old fossil fish they thought could be the missing link between aquatic and land-dwelling creatures. They would have loved to study it, but it had gone extinct with the dinosaurs.

Or so they thought. Until 1938, when a museum curator saw a fisherman haul one out of his net in South Africa. She wrote a hasty telegram to her museum. They wrote back: “Get that fish!”

She had found the coelacanth, not extinct after all, but hiding for millions of years in the Indian Ocean.

True to the fossil, it had small pectoral fins, on arm-like stalks, connected to joints like shoulders, and a wide fleshy tail.

According to local reports, it was so oily and foul tasting that anyone who tried to eat it would become sick. Which probably helped this slow growing living fossil keep on living.

And researchers soon found it’s very slow indeed. Coelacanths can grow to 200 pounds and live to 100 years but don’t reach sexual maturity until they hit 50.

Females incubate eggs within their abdomen, which take 5 years to hatch, then emerge as live young—the longest gestation of any animal.

It turns out, however, the coelacanth wasn’t the missing link that scientists hoped for. That honor belongs to its relative, the lungfish, which crawls out of the water to make short journeys on land.

There are no snakes in Ireland. Because, according to legend, St. Patrick expelled them. True, or folk tale?

St. Patrick, ironically, wasn’t Irish. Or, named Patrick. He was born Maewyn Succat in 390 AD in Britain, kidnapped by pirates at 16, and held in slavery in Ireland for 6 years.

He escaped and joined a monastery in England. Then decided to return to Ireland as a missionary, where he converted Druids and built the first church.

He died in 460 AD in Downpatrick, hence the name. A few centuries later, he was recognized as Ireland’s patron saint for bringing Christianity to the land.

A few centuries after that, his mythology had grown. Apparently, the snakes of Ireland once threatened him on a hilltop. He responded by beating a drum that drove them into the sea.

Scholars believe this is a symbolic tale of Patrick purging Ireland of its pagan rituals.

Scientists argue that Ireland never had snakes in the first place.

In the last Ice Age, Ireland was covered in glaciers, much too cold for the cold-blooded creatures. Since the ice retreated, Ireland has been isolated by the frigid Irish sea.

There are other isolated islands, like New Zealand and Hawaii, that don’t have snakes. And other cold regions, like Alaska and Northern Russia. So, it’s not as unusual as it sounds.

But it makes for a good story over a green beer.

Penguins have been around a long, long time.

They first evolved more than 60 million years ago when the asteroid that wiped out the dinosaurs opened a niche for them.

Fossils suggest they were already flightless, but they took to the sea where they became perfectly adapted:

Their feathers are coated in oil. Their body is insulated in fat. Their wings are shaped like flippers, making some penguins twice as fast as the fastest human swimmer.

Their bowling-pin shape doesn’t look athletic, but in the water they’re a tuxedoed torpedo.

That signature black and white coloring hides them from predators and prey. From above, they blend into the ocean darkness. From below, they look like the white sky.

Though some early penguins stood as tall as a human, they’ve diversified into 17 different species, from the largest 80-pound Emperor to the tiny fairy penguin.

Some species spend 75 percent of their time at sea—enough to grow barnacles on their feathers.

Others can dive to 1,500 feet in search of food and hold their breath for half an hour!

Each year around April 25th, the Adélie penguins of Antarctica begin a long migration from their summer breeding grounds to their winter feeding grounds. A few weeks later, their larger Antarctic cousins follow suit.

So, scientists have designated April 25th as World Penguin Day. A good time to celebrate this weird and wonderful swimming bird.