Impact event

An impact event happens when a space rock, like an asteroid or comet, crashes into a planet. These rocks travel very fast! When they hit, they can make giant holes called craters.

Scientists believe a massive impact 66 million years ago caused the dinosaurs to die out.

A "wow" fact is that a space rock once hit Jupiter and left a dark scar the size of Earth!

Most small rocks explode high in the air before they reach the ground. This is called an airburst. We now have telescopes to watch for these rocks to keep us safe.

An impact event is a collision between objects in space, such as asteroids, comets, or meteoroids. When these objects enter Earth's atmosphere, they travel at least 11 kilometers per second!

Many small rocks explode in the sky, creating a powerful "airburst" that can break windows, like the Chelyabinsk meteor did in Russia in 2013.

Impacts have shaped our world's history. Scientists think the Moon was formed when a planet-sized object crashed into the early Earth.

Another famous impact happened 66 million years ago at Chicxulub in Mexico. This event caused a mass extinction that ended the age of the dinosaurs but allowed mammals to thrive.

Today, we use systems like NASA’s Sentry to track "Near-Earth Objects" (NEOs). In 2022, humans successfully changed the path of an asteroid for the first time using the DART mission. This proves we might be able to protect Earth from future hits.

An impact event is a collision between astronomical objects, such as asteroids or comets, that causes measurable effects. These events have played a massive role in the history of our Solar System. For example, the leading theory for the origin of the Moon is the "giant-impact hypothesis," which suggests a Mars-sized object struck the early Earth.

Impacts may have even delivered the water and chemical building blocks necessary for life to begin on our planet.

When an object strikes Earth, it travels at a minimum speed of 11 km/s, which is the Earth's escape velocity. The damage caused depends on the object's size, speed, and density. Large objects can create massive impact structures. For a long time, people thought craters like the Barringer Crater in Arizona were volcanic. However, in 1963, scientist Eugene Shoemaker proved they were caused by meteorites.

In modern history, we have recorded several significant events. In 1908, the Tunguska event in Siberia flattened 80 million trees over a huge area, likely caused by an asteroid exploding in the air.

More recently, in 2013, a meteor exploded over Chelyabinsk, Russia. The shockwave from this airburst injured over 1,500 people, mostly from glass shattering in buildings.

Scientists are now working hard on "planetary defense." We track Near-Earth Objects (NEOs) to predict future collisions. While small asteroids hit Earth frequently, large ones are rare. An asteroid 1 km wide strikes Earth roughly every 500,000 years. To prepare, NASA launched the Double Asteroid Redirection Test (DART) in 2022.

This mission successfully crashed a probe into an asteroid named Dimorphos, changing its orbital period by 32 minutes. This was the first time humans successfully moved a celestial body, proving we have the technology to potentially deflect a dangerous asteroid in the future.

Impact events—collisions between astronomical bodies—are among the most powerful geological and biological drivers in the Solar System. These events occur when asteroids, comets, or meteoroids strike planets or moons at hypervelocity. Because Earth has an escape velocity of 11 km/s, any object striking our planet must be traveling at least that fast, resulting in the release of immense kinetic energy. This energy can trigger shock waves, tsunamis, earthquakes, and massive thermal radiation.

The history of Earth is defined by these collisions. The giant-impact hypothesis suggests that the Moon was formed when a Mars-sized planetoid struck the Earth four billion years ago.

Furthermore, the Late Heavy Bombardment period saw thousands of impacts that shaped the crusts of the inner planets. Some scientists even propose the theory of exogenesis, suggesting that comets delivered the water and organic molecules that allowed life to emerge.

Geologically, impact cratering is the most widespread process in the Solar System. On Earth, many craters are hidden by erosion, but structures like the 2-billion-year-old Vredefort crater in South Africa and the Hiawatha crater buried under Greenland's ice provide evidence of massive prehistoric strikes.

It was not until the work of Eugene Shoemaker in the mid-20th century that scientists realized many "volcanic" features were actually impact sites.

Shoemaker also co-discovered Comet Shoemaker-Levy 9, which famously collided with Jupiter in 1994, providing the first direct observation of an extraterrestrial impact.

The most famous biospheric effect of an impact is the Cretaceous–Paleogene extinction event 66 million years ago. Physicist Luis Alvarez and his team discovered a global layer of iridium—an element rare on Earth but common in asteroids—dating to this period. This led to the discovery of the 180 km-wide Chicxulub crater in Mexico.

This impact caused the extinction of non-avian dinosaurs and paved the way for the rise of mammals and, eventually, humans.

In the modern era, the 1908 Tunguska event and the 2013 Chelyabinsk meteor serve as reminders of our vulnerability. The Chelyabinsk event involved a 20-meter object that exploded with 30 times the energy of the Hiroshima bomb, injuring 1,500 people.

Today, organizations like the B612 Foundation and NASA’s Sentry system monitor the skies for Near-Earth Objects. While we have identified 95% of asteroids larger than 1 km, smaller objects remain difficult to detect before they are on final approach.

Humanity has recently moved from passive observation to active defense. In September 2022, the Double Asteroid Redirection Test (DART) successfully deflected the asteroid Dimorphos.

By changing the asteroid's orbital period by 32 minutes—well exceeding the 73-second success criteria—NASA demonstrated that we possess the capability to alter the trajectory of a threatening object. As physicist Stephen Hawking noted in his final book, an asteroid collision remains one of the greatest threats to our planet, but for the first time in history, we have the potential to prevent one.