EarthDate

Have you ever seen those beautiful satellite images of Earth and wondered what camera could take them? The answer is no camera could. They’re produced by a multispectral scanner developed in the 1950s at Hughes Aircraft by a team led by the young MIT scientist Virginia Norwood—known today as the “Mother of Landsat.” Landsat, Earth-imaging satellites, were first launched in 1972 by NASA with the go...

Three times in Earth’s long history, a process called endosymbiosis has occurred. And it has totally changed life on Earth. Two billion years ago, all life was single-celled organisms in an oxygen-free environment. Some of these bacteria-like creatures engulfed others into their cell walls and began a symbiotic relationship called endosymbiosis. The smaller organisms became organelles within the l...

For thousands of years, humans have found shelter in lava tubes. In the future, they may do the same—on the Moon! A lava tube is a cave. It forms when lava flowing in a channel forms a crust on the upper surface that’s exposed to cooler air. The crust insulates the lava below, which gets superheated and melts a deeper tube-shaped channel as lava continues to flow through it. When the lava runs out...

Ozone makes up a tiny portion of Earth’s atmosphere, but it allows for life on Earth. The oxygen we breathe is what’s called molecular oxygen, O2—two atoms of oxygen bonded together. High above Earth’s surface, in the stratosphere, the Sun’s intense radiation splits those oxygen molecules, and a tiny fraction reform as ozone, or O3—three oxygen atoms, with a very important property. Ozone absorbs...

Solar flares and coronal mass ejections are the most powerful explosions in our solar system—too large, heavy and fast-moving to imagine. But they’re not the same thing. They occur mostly when the Sun’s magnetic poles prepare to flip, every 11 years or so, in an event called a “solar maximum.” Magnetic fields deep within the Sun punch up to create two very different anomalies on the surface: Solar...

Dinosaurs, like most large animals today, had long lives. Therapods like T. rex lived to about 30 years, while giant sauropods could live to 60. And over those long lifespans, like all of us, they got sick. Soft tissues don’t fossilize as well as bone, but scientists have documented diseases, from the mundane to the mortal, in all types of dinosaurs. Feathered dinosaurs had dandruff. Others showed...

It may appear that tides come in and out. But that’s not really what happens. In fact, the Moon pulls the ocean toward it, creating what’s called a “tidal bulge” of higher water surface. The tidal bulge happens on the side of Earth facing the Moon, with a balancing but slightly lower bulge on the other side of Earth. As Earth rotates, land masses come into contact with these higher water levels an...

Many evolutionary advances, like big brains, have given humans an advantage over other animals. Perhaps one of the least appreciated is the thumb. Specifically, the opposable thumb--meaning opposite our fingers--with the ability to touch each finger across the palm, enabling our hands to manipulate small objects. Around 400,000 years ago, Neanderthals had opposable thumbs, but they were much less...

On September 17, 2024 we’ll have a Super Harvest Bloody Moon. Kind of a fantastical, creepy name, but those three adjectives each describe a different celestial event, which will coincide in this one moon. A Harvest Moon is the full moon nearest the autumnal equinox, called that because it gave farmers some extra light to bring in their crops. There’s a Harvest Moon every year, but not often so cl...

The first dinosaur fossil documented by a scientist was 350 years ago, in 1677. It was part of a femur discovered in a shale mine in England, then sent to a local museum. The curator had never seen anything like it. He thought it must be a thigh bone from a war elephant, from some ancient battle. Or the femoral head of a giant human, as described in the Bible. At any rate, he published an illustra...

Sharks have been so successful, for so much longer than so many other lifeforms, that you could call Earth the shark planet. They evolved over 400 million years ago, meaning they’re older than trees. They’re 6 times older than the North Star! And over a thousand times older than humans. They’ve survived all 5 known mass extinction events. Over that long, long period, they’ve diverged into hundreds...

For nearly 60 years, an international deep ocean drilling program has revolutionized earth science and understanding. Two research ships in particular, the Glomar Challenger, later replaced by the JOIDES Resolution, have drilled hundreds of miles of ocean sediment core, in every ocean. These cores provide a record of Earth stretching back millions of years. They’ve allowed scientists to validate t...

In 1797, in central Kentucky, a hunter chased a bear into a hole in a cliff … and discovered the longest cave network in the world, 10 million years in the making. But at that time, all he could see—and smell—was bat guano, which was then the valuable source of saltpeter, a key component in gunpowder. Within a year, prospectors were mining centuries of bat droppings for military efforts. During th...

You might think that plants are stationary, but did you know they can dance? Many flowers do a daily sun dance, swinging from east to west, to produce more pollen and attract insect pollinators. They make this movement using two methods: Plants contain a compound called phototropin that responds to being in shadow by causing cells to elongate. In this way, the dark side of the plant grows longer,...

In the beginning, Earth was hell. The planet was completely molten, a roiling sea of magma at temperatures of thousands of degrees. Scientists even referenced Hades to name this period: Hadean Earth. How did it become the green paradise we know today? Well, over about half a billion years, it cooled. And how it cooled has shaped some important traits of Earth to this day. Logically then, scientist...

For millennia, people have been drawn to volcanoes. Why? Because before they arrived, the volcanoes had erupted. Their lava, ash and debris covered the surrounding area, making for fertile farmlands that drew settlers … who may not have recognized that the volcanoes could erupt again. And that’s just what happened around Italy’s Mount Vesuvius. Long before the Romans, people had come to farm there...

Last EarthDate, we talked about the eruption of Mount Vesuvius, which completely covered Pompeii in ash. Within a century, the city was forgotten. Until the 1500s, when an architect dug into a room. It had once been a brothel, with explicit frescoes on the wall. Considering them inappropriate, he buried them again. In the 1700s, artifacts were discovered in a vineyard in the volcanic soil above th...

Every 11 years, the Sun cycles from solar minimum to solar maximum, as we discussed in a prior EarthDate. And we’ve just entered another solar maximum, where the Sun emits many more charged particles in a faster, stronger solar wind moving toward Earth. You might experience it in disrupted GPS or cellular signals. But you can see it in the night sky. Specifically, in the aurora borealis, the famou...

You might not think a river can burn. But in 1969, the Cuyahoga River that runs through Cleveland caught fire. The Cuyahoga was the most polluted river in the country, so fouled with industrial waste and sewage that it was completely devoid of life when a spark from a passing freight train ignited an oil slick that covered the water. The river had burned at least 10 times in the previous 100 years...

One of our greatest scientists was given an aristocratic title by Parliament. But he began life simply, as a math teacher’s son. William Thomson was born in Belfast, Ireland. His father moved the family to Glasgow for a job at the university. He started William in classes at 10 years old. Immediately, his talent began to shine. In his teens, he published three papers on the relationship between he...

Drinking salt water is poisonous to humans. It’s four times saltier than our blood, so our kidneys pull water from our tissues to try to balance the seawater, which could lead to dehydration or death. Whales and dolphins, seals and walruses are all mammals, and they need fresh water too. But they live in salt water. So what do they drink? Nothing! Their digestive systems are superefficient at pull...

If left unprotected, something made of iron will dissolve into dust. That’s because of rust. Some metals, like gold and platinum, are naturally stable and keep their shiny appearance. Other metals like aluminum, copper and silver develop patina or tarnish that protects the raw metal beneath. Iron is different. It’s the most abundant element on Earth, followed by oxygen—together they make up over 6...

The world’s most successful research submarine, Alvin, has completed over 5,000 dives in its 60-year career. Its first mission, in 1966, was to search for—and find—a hydrogen bomb that had fallen into the deep ocean. Two years later, cables snapped while Alvin was being lifted aboard its tender ship, and it sunk to the bottom of the Atlantic … where the sub itself had to be retrieved. It has been...

Native American legend says the Creator, when done forming Earth, threw all the leftover rocks into a pile in West Texas—a jumble of geology that today we call Big Bend. It gets that name because it sits in a 200-mile-long curve in the Rio Grande River that separates Texas and Mexico. Big Bend is now a nearly million-acre national park—with a protected area twice as large on the Mexican side of th...

Big Bend is one of the largest, most remote and least visited national parks in the U.S. It’s a land of great diversity. More than a mile of elevation change. More than 100 degrees Fahrenheit of temperature fluctuation annually. Diverse topography—deserts, mountains, canyons, rivers and springs—with different life in each ecozone. And because of that, more ecological diversity than any other natio...