The theory of plate tectonics was not initially accepted until evidence became undeniable

The theory of plate tectonics first emerged from the theory of continental drift

German meteorologist Alfred Wegener proposed that the continents were all one giant landmass in the past, which he named Pangaea. Despite geological and climate evidence suggesting continental movement, his theory was dismissed until the 1960s.

Records of Earth's magnetic field on the seafloor validated plate tectonics

Matching glacial, fossil, and rock records, mountain ranges, and continental shapes across oceans was insufficient evidence for continental drift. Precise measurements of magnetic minerals on the ocean floor revealed seafloor spreading, which could only be explained by moving landmasses.

Continental drift is supported by matching evidence across disconnected continents

Mesosaurus fossils are found in South America and Africa, but these freshwater creatures could not have travelled across the ocean between continents. Rock layers in the Appalachian Mountains match those seen in Europe, indicating that the mountain belts were once connected.

The discovery of the Mid-Atlantic Ridge was initially dismissed as ‘girl talk’

Marie Tharp identified the structure when mapping the ocean floor using sonar data, but her colleague, who did not favor continental drift, was unconvinced. Famed filmmaker Jacques Cousteau even tried to disprove her work with underwater footage, only to validate her maps.

Convection flows in Earth’s mantle drive the movement of tectonic plates

These processes transfer heat from Earth’s core to the surface via rising magma plumes, while cooler, denser rock falls into the mantle at rates similar to human fingernail growth. These rates are determined by combining seismic data with computer simulations to model Earth’s interior.

The Rodinia supercontinent triggered a global ice age when it broke 750 million years ago

Before Pangaea, the Earth’s continental plates had drifted together and broken apart multiple times, with each event altering atmospheric CO2 concentrations and triggering climate change. The continents are estimated to come together again in 50 million to 250 million years.

Explore case studies of each type of convergent plate boundary

At these boundaries, a collision of two oceanic plates produces a curved chain of volcanic islands, like those seen in the Caribbean. A continental-continental plate collision results in plates buckling upward, forming large mountain ranges.

Remnants of another planet that helped form the moon may be beneath Earth's surface

Large mantle structures beneath Africa and the Pacific Ocean may be the buried remains of Thea, a large Mars-sized planet that collided with Earth. The theory is supported by isotopic evidence from volcanic and lunar rocks.

Paleontologists apply rules about rock layering, fossilization, and radioactivity to date geological samples

Concepts such as the understanding that older rock layers will form beneath newer ones allow scientists to compare the ages of samples from various layers. Although no geological site preserves evidence across all time, samples can be combined with fossils of known age, such as those dated by analyzing the decay of their radioactive isotopes, to reconstruct Earth's timeline.

Travel through deep time with this interactive Earth

Explore key moments in Earth’s transformative history as continents drift and climate fluctuates over 4.6 billion years. The Smithsonian presents a series of interactive snapshots of the earth. From its toddler years during the Hadean period, when its surface was mostly molten, to the mostly unidentifiable landmasses of the future earth, 100 million years from now.

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.

The missing continent that took 375 years to find

It took scientists 375 years to discover the eighth continent of the world, which had been hiding in plain sight all along. But mysteries still remain.

Explaining why animals don't cross this invisible line in Indonesia

Although the distance separating the two regions is small, East and West Indonesia have starkly different species, puzzling scientists for decades. Biogeographers use the theory of plate tectonics to explain the phenomenon, arguing the two regions...

Abiogenesis explains how Earth's natural processes could have formed organic matter

The theory details how chemical interactions in hydrothermal vents and shallow ponds billions of years ago could have created lipids, proteins, and RNA. As these interactions involve water, life is thought to have started in oceans.

Explaining why the Earth wobbles

Astronomers going back to Hipparchus in the 2nd century BCE have noticed our planet has a distinct wobble. More recently, scientists have observed that the Earth is 26 miles wider at the equator than from pole to pole. The wobble results from our...

The Big Bang theory describes how the universe began and continues to expand

Rooted in Lemaître’s 1927 idea of a growing universe and confirmed by Hubble’s redshift data, the theory is backed by evidence like cosmic microwave background radiation—remnants of the universe’s fiery birth detected in the 1960s. The radiation was first misidentified as interference from pigeon droppings inside a telescope antenna.

Cell theory originated from microscopic observations of cork and dental plaque

In the mid-1600s, Robert Hooke identified compartment-like structures—which he called cells—in cork, and Anton van Leeuwenhoek discovered bacteria in samples of his dental scrapings. Almost 200 years later, Matthias Schleiden and Theodor Schwann showed that plants and animals, respectively, are composed of cells, proving that cells are the foundation of all living things.

One researcher posed a theory that aliens played a significant role in human evolution

Researcher Zecharia Sitchin proposed that Sumerian cuneiform tablets revealed that Sumerian gods were aliens who landed on Earth in Mesopotamia and influenced the creation of modern humans. While his ideas gained cultural interest, they are widely rejected by mainstream scholars.

Why David Attenborough was skeptical about global warming before bringing attention to it

Believing he was "experiencing the untouched natural world" in his early documentary series, Attenborough has admitted that many of his assumptions about human action were incorrect. It was not until attending a 2004 lecture on greenhouse gases and global temperatures that he became convinced of the science.

A list of five scientific theories that were accepted and later disproved

Humoral theory held that everyone's personality derived from different combinations of four bodily fluids: blood, phlegm, yellow bile, and black bile. The phlogiston theory stated that all combustible materials possessed a fire element—phlogiston—that was released and absorbed by the air during burning. When the air became saturated with phlogiston, the fire would go out.

Portugal's 1775 earthquake is considered Europe's first modern natural disaster

An 8.5-magnitude earthquake off the Portuguese coast nearly destroyed Lisbon, killing thousands, creating 16-foot-wide fissures in the city, and triggering a massive tsunami. Historians credit it with jump-starting the Enlightenment in the region, with many thinkers seeking natural explanations.

How a solar eclipse proved Einstein's theory of gravity

For hundreds of years, Isaac Newton's laws of gravity and motion accurately predicted every observation and measurement involving orbits. With the advance of technology, more precise measurements revealed anomalies, including the orbit of Mercury, which Albert Einstein's general theory of relativity could explain. This article details the two frameworks and how they went head-to-head during an eclipse for gravitational supremacy.

Review an historical exploration of Charles Darwin's expeditions

Darwin spent more than half of the Beagle expedition in Patagonia, discovering large mammal fossils, including extinct sloths. He journaled about the Argentine genocide of Indigenous peoples in the regions while making findings that would contribute to his theory of evolution.

How upheavals in accepted scientific theories helped popularize the term 'paradigm'

When Thomas Kuhn published "The Structure of Scientific Revolutions" in 1962, he described the history of science as comprising periods of "normal science" where these accepted frameworks—paradigms—gradually accumulate anomalies until they cannot describe nature. Revolutionary science, such as the development of a new theory, results in a paradigm shift, another term Kuhn helped popularize. (Some readers may experience a paywall.)

Dow Theory laid the groundwork for modern market analysis

Developed by Charles Dow in the late 19th century, Dow Theory argued that markets move in trends. Its principles—confirmation, trends and volume—still influence technical analysis today.

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.

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.

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

The history of many kitchen appliances involves unexpected discoveries and applications, including wartime radar turned hamster defroster and replacing an 'ice king' with heat-stealing boxes.

Explore the animals that populate the depths of the ocean, from fish and coral in the first few hundred feet, all the way down to the bottom of the Mariana Trench.

The American cockroach is actually from Africa, an apparent hitchhiker aboard ships carrying enslaved people, with evidence suggesting the bug may have arrived in the New World as early as the 1600s.

The concept of phantom limbs, the perception that amputated limbs are still present, dates back to a French military surgeon in the 16th century.

A researcher recently discovered an interview from 1967 between groundbreaking journalist Joan Didion and the Grateful Dead, years before the band became an institution.

While the sun's gravity keeps the planets in orbit, their gravity also pulls on the sun, causing it and everything else in the solar system to orbit around a mutual balance point called the barycenter—the true center of the solar system.

While El Niño moves warm Pacific Ocean waters east along the equator, La Niña moves them west, shifting where rainfall will become more common for months.

Walt Disney's early film 'Alice's Wonderland' was a groundbreaking innovation in the silent film era

How fusion—which releases energy when two lighter atoms combine to form a heavier atom—differs from fission

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.

Explore fun facts from the USPS, including unique post office buildings, a stamp that traveled past Pluto, and more.

The Dracula character, now seen as the vampire archetype, was inspired by a seafood-induced nightmare its creator experienced.

Meet the 56 signers of the Declaration of Independence—most of whom didn't put pen to paper until August 2, 1776—and see their original signatures.

'Grand Canyon of the Yellowstone,' a work by American painter Thomas Moran, inspired Congress to establish Yellowstone National Park.

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

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

Domino's Pizza's 30-minute delivery guarantee was responsible for the chain's 1980s surge, but it was discontinued after the company was found liable for delivery driver accidents.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

As of 2025, the most cited papers in science include a review of graphene, methods to improve image recognition, streamlining electron density calculations, and optimizing protein studies.

70 years ago today, city officials in Santa Cruz, California, banned rock 'n' roll to protect its youth from corruption after witnessing a 'provocative' concert the night before.