The majority of dinosaurs (apart from the bird line) went extinct when an asteroid hit Earth about 66 million years ago, starting a series of events that eventually caused a mass extinction.

According to the scientists research conducted by Luis Walter Alvarez, Walter Alvarez, Sean Gulick of the University of Texas at Austin, and Paul Barrett of the Natural History Museum (UK), the most strong evidence suggests that the Chicxulub impact happened on the Yucatán Peninsula in Mexico and that there was a worldwide spike in iridium in rocks of that age.

Their research explains not only what struck Earth but also what took place there and why life changed forever.

What happened to the asteroid on that impact

The asteroid size was about six miles.

According to Sean Gulick of the University of Texas at Austin, it struck with “the energy of about 8 billion times a World War II-era nuclear bomb,” as he told Live Science. The asteroid “basically vaporizes” at that size instead of bouncing or breaking into large pieces. For many years, a large portion of it became “a fine dust that ends up in the upper atmosphere and rains down.”

A good deal of the asteroid became fine dust after the impact, which floated around the planet before gradually falling back down. Than thin layer of 66 million-year-old rocks left by that global “dust fall” is weirdly rich in iridium, a metal that is common in space but rare on Earth. Which indicates that the dust originated from the asteroid.

“The most widely accepted theory” for the end-Cretaceous mass extinction is the Alvarez hypothesis, according to the Natural History Museum (UK). A theory in the early 1980s where he accepted the connection between the iridium spike and the impact.

Chicxulub and the worldwide consequences

It wasn’t just chemistry there’s huge and obvious scar: Near Yucatán Peninsula, in Mexico, the Chicxulub asteroid left behind a crater that is more than 100 miles in diameter and mostly buried beneath the seafloor. Since it happened during with the mass extinction, scientists link it to the impact.

Paul Barrett of the Natural History Museum (UK) claims that “there was total devastation in the immediate area.” The trash was thrown into the air by a massive explosion and heat wave, spread all that ash globally.

The veil was very thick to make a difference but it wasn’t total darkness: According to Barrett, “it decreased the amount of light reaching the Earth’s surface, but it didn’t totally block out the sun.” Less light made it harder for plants to grow. Carnivores lost their prey first, then herbivores followed. The food chains broke up. Barrett ends by saying, “It was a significant event that affected all life on Earth.”

Why this story convinced scientists

There are three points of evidence that are consistent:

• Physics: A six-mile space rock hits so strongly that it essentially turns into vapor and sends tiny particles of dust up in the air.
• Geochemistry: At the moment of impact, they discover a thin global layer of rock rich in iridium, a metal that is common in space but rare on Earth.
• Geology: Chicxulub, a massive crater on Mexico’s Yucatán Peninsula, is situated in the ideal location and at the ideal age.

Together, these scientists today explain how a single blow changed the course of life and why dinosaurs (apart from birds) went extinct.

A tiny world impacted by powerful forces

These “evidences” shows how a single asteroid impact can cause a mass extinction producing changes everywhere in different ecosystems, climate, and atmosphere.

And scientists and researches in geology, chemistry, and paleontology it’s what allow us to understand how all of this happened, how Earth’s existence and ours was altered by just one impact a long time ago.