There have been five mass extinction events in Earth’s history

The resulting climate change, not the asteroid impact itself, killed most dinosaurs

Although the Chicxulub impact caused widespread destruction through earthquakes and tsunamis, the subsequent nuclear winter, acid rain, and eventual greenhouse warming drove mass extinction. Roughly 70% of species, including all non-avian dinosaurs, went extinct.

Dinosaurs emerged 245 million years ago when Earth’s continents were still conjoined

Once the supercontinent split apart, dinosaurs evolved into thousands of species as they adapted to their changing environments. All non-avian dinosaurs went extinct about 66 million years ago following an asteroid impact, while avian dinosaurs evolved into today’s birds.

Rapid environmental changes are exacerbating natural extinction processes

Human activities behind climate change, habitat destruction, pollution, and overhunting have resulted in extinction rates up to 1,000 times greater than normal, triggering massive biodiversity loss. This has led scientists to refer to the current geological age as the Anthropocene era, in which humans are the dominant force shaping nature.

Georges Cuvier used his knowledge of anatomy to prove extinction had occurred

Extinction had been viewed as impossible because a divine plan for the world would not rationally involve the loss of any of God’s creations. However, mammoth and mastodon bones differed from elephants’, and it seemed impossible that such creatures could be hiding elsewhere on Earth.

Mammals gradually expanded in size and diversity after the dinosaur extinction

After an asteroid impact caused a mass extinction event 66 million years ago, small mammals were among the few surviving species. With fewer predators, mammals steadily grew larger as new habitats emerged.

Underwater volcanoes significantly contributes to marine extinctions during the Triassic period

An analysis of ocean basins in the Tibetan Plateau helped identify three major periods of volcanism—250-248, 233-231, and 210-208 million years ago—which released significant amounts of greenhouse gases, altering ocean chemistry. The low-oxygen conditions may help explain half of Earth's Triassic extinctions.

What did the world of the dinosaurs look like?

Mesozoic means "middle life" and this is the time of the dinosaurs. This era includes the Triassic, Jurassic, and Cretaceous Periods, names that may be familiar to you. It ended with a massive meteorite impact that caused a mass extinction, wiping out the dinosaurs.

Humans have existed for just 0.004% of Earth’s history

Born from the remains of the molecular cloud that birthed the sun, Earth experienced planetary-scale collisions, asteroid impacts, and lava seas. Life became possible after the planet cooled and formed a thin crust, atmosphere, and oceans.

Why genetic similarities between humans suggest a past near-extinction event

Researchers have found that low genetic diversity among humans—even those on opposite sides of the planet—may result from a breeding population of as few as 1,280 adults, estimated to have existed 930,000 years ago. This genetic bottleneck may have resulted from a near-extinction or from a small population of human ancestors, from which we all descend, that broke off from a larger population.

The world, one year after humanity goes extinct

The Earth is so shaped by human action, it's hard to imagine what it would look like without us. This brief, digestible explainer for kids highlights what a humanless world would look like one year after the extinction event.

View a breakdown of the identified species on Earth

Over 2 million species have been documented by scientists, but there may be as many as a billion distinct species. The vast majority of the species on Earth are insects, while mammals form the smallest group.

From 2023 to 2025, coral reefs experienced their fourth global bleaching event

Heat stress from the 33-month-long event impacted about 84.4% of the world's coral reef area across waters in at least 83 countries and territories, making it the largest such event to date. Due to climate change, about 90% of coral reefs are expected to undergo bleaching annually by 2050, leaving insufficient time for recovery during the winter months between bleaching events.

Ice ages are periods of glaciation that last tens of millions of years

During these periods, Earth grows cold and is covered in massive continental ice sheets. Scientists have outlined at least five major ice ages, which result from the alignment of complex factors, like the flow of ocean currents and the movement and location of tectonic plates.

Ten impact craters you can visit

See photos of ten wild Earth impact craters across the world, the result of impacts occurring between thousands and millions of years ago.

T. rex needed the same amount of calories as 80 people every day

Tyrannosaurus rex is the most extensively studied fossil creature ever known. Every year, new research is added to the towering list of papers that try to draw …

The last Pinta Island tortoise died in 2012 at over 100 years old

Unfortunately, different animal species continue to go extinct. See a list of these recent extinctions, and learn the story of Lonesome George, who died without finding a mate in the Galapagos Islands.

Humans won't develop more than 5 fingers because it would impact too many body parts

All modern animals have five or fewer digits on each of their limbs. Roughly 348 million years ago, at least two species had eight: the Ichthyostega and the Acanthostega. According to Dollo's law, complex evolved features are very unlikely to recur in evolution. Researchers believe humans won't develop more than five digits because it would impact other body parts too much.

View the 10 biggest volcanic eruptions in recorded history

The Mount Tambora eruption in 1815 was the deadliest and released so much sun-blocking ash and gas that 1816 became known as “the year without summer.” The resulting global food shortages are estimated to have killed over 71,000 people.

Butterfly populations have declined by 22% from 2000 to 2020

Research suggests that one in every five butterflies is lost due to pesticide use, habitat loss, and climate change. Playing a vital role in pollination, their declining populations threaten plant reproduction and the health of ecosystems.

Earth Day has become the largest civic event in the world

What began in 1970 with 20 million Americans now involves more than 1 billion participants across over 190 countries each year. Earth Day now encompasses rallies, cleanups, and climate actions worldwide.

Could the world's largest solar storm happen again?

In 1859, the world witnessed the most intense solar storm in recorded history. The electromagnetic deluge of dust and gas lit up the night sky and sparked fires, disrupting Earth's magnetic field and putting on a show for the millions. If a storm with a similar intensity today occurred, scientists believe it would be catastrophic for our communications systems. Learn what would happen if the Carrington Event happened again here.

From 1970 to 2017, invasive species have caused $1.28T in damage globally

The costliest species were the Asian tiger and yellow fever mosquitoes ($149B), which arrived in the US from Asia and sub-Saharan Africa, respectively. The bulk of their damage came from their transmission of diseases such as Zika, chikungunya, and dengue. (Some readers may experience a paywall.)

Watch every episode of David Attenborough's 'Life on Earth' series

A three-year global expedition by Attenborough and his team produced the television series, which debuted in the UK in 1979 and documented over 600 species in 40 countries. The series is estimated to have been seen by over 500 million people in more than 100 territories, including within the US, where is debuted on PBS in 1982.

Variola: the second-deadliest virus on Earth

Because it was declared eradicated in 1980, many forget smallpox is one of history's deadliest diseases—in its final century, it's estimated to have claimed 500 million lives. This 11-minute video from production studio Kurzgesagt takes a look at...

After swallowing 23 pieces of plastic, seabirds experience a 90% death rate

Researchers found that this threshold is also met when marine mammals ingest 29 pieces and when sea turtles consume approximately 405 pieces. Almost half of the sea turtles, a third of the seabirds, and one in ten of the marine mammals studied had eaten plastic.

Indefinite cloning of some endangered species may not sustain their longevity because cloning success rates decrease as genetic mutations accumulate.

View the ten deadliest tornadoes in US history.

See how each of the more than two million known species relates to each other—and to common ancestors—in this zoomable tree of life.

Three Ebola species are responsible for most large outbreaks of the disease, yet the only approved Ebola vaccine is known to work against just one of them.

Scientists can determine Earth's past climate conditions by analyzing air trapped in microscopic bubbles within ice cores—columns of compressed snow layers that build up over hundreds of thousands of years.

Volcanic activity may have triggered the Black Death by spewing gases that led to crop failures in Europe, thus forcing the import of grain ships with plague-infested fleas.

After NASA's Voyager 1 captured Earth as a single pixel as it left the solar system in 1990, astronomer Carl Sagan used the image to reflect on humanity's fragility and the responsibility to protect 'the only world we've ever known.'

About 12.5% of US adults experience a phobia in their lifetime, a diagnosis that hinges on the intense fear interfering with daily life and persisting for at least six months.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

Neutron stars, the remains of some massive stars after they explode in a supernova, are the densest directly observable objects in the universe.

See the 25 of the best photos of auroras from around the world.

Chaos theory—informally known as the butterfly effect—is the reason why weather forecasts are presented with probabilities rather than certainties.

Some renewable energy sources may weaken the resiliency of electric grids by removing outage buffers provided by coal- and natural gas-fired plants, which provide the system with more time to find a new power source if a plant goes down.

While the first exchange-traded fund (a 'basket' of different assets that can be bought and sold on a stock exchange) in the US only launched in 1993, the global ETF market has grown to more than $10T in the short time since.

Fireworks-related ER visits are on the rise—in 2024, they increased by 52% as compared to the prior year.

The Russia-Ukraine conflict is the largest ground war in Europe since World War II in casualties, forces mobilized, and displacement of civilians.

Apollo astronauts left items in the moon's 'toss zone,' including golf balls, family photos, and bags of human waste, to make room for lunar rocks.

Fish populations in the Great Barrier Reef have increased after installing waterproof speakers on the ocean floor that played recordings of sounds from healthy coral reefs.

In 2018, 26-year-old missionary John Allen Chau was killed by tribesmen after attempting to reach and evangelize on India's isolated North Sentinel Island

A 2019 Facebook event called on attendees to "Storm Area 51, They Can't Stop All of Us," resulting in countless memes, the creation of a music festival, and eventually the arrests of those who did try to approach the area.

In 2019, a laptop loaded with six of the worst malware in history and described as 'an exhibit of historical weaponry' sold for $1.3M.

Before writing 'Walden,' transcendentalist Henry David Thoreau nearly burned down his hometown with a campfire that grew out of control.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

See a 3D reconstruction of Tenochtitlan, the Aztec capital that was home to an estimated population of 200,000 to 400,000.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year