What was the biggest meteor to ever hit our planet?

In one line

The rule

A meteor (also called a meteoroid before entering Earth's atmosphere) is a space rock that enters Earth's atmosphere and hits the ground, making a crater if it is big enough.

Let's understand it simply

Imagine you are playing cricket and a big stone suddenly falls from the sky onto the ground. It makes a huge hole. Now, think of a stone so big that it is even larger than a city, falling from space at a speed faster than any train or plane. When this giant rock hits the Earth, it makes a crater (a big bowl-shaped hole) and changes everything around it. This is what happened with the biggest meteor known to have hit our planet.

How it works

1. A huge rock (asteroid) travels through space.
2. It enters Earth's atmosphere at a very high speed (about 20 km per second).
3. The rock gets very hot and bright as it passes through the air (this is what we call a meteor or shooting star, but most are much smaller).
4. If the rock is big enough, it does not burn up and hits the ground, making a giant explosion.
5. The impact creates a massive crater and throws dust and rocks into the air.
6. This dust can block sunlight and change the climate for years.

The story behind it

The Chicxulub impact happened about 66 million years ago, near what is now the town of Chicxulub in Mexico's Yucatán Peninsula. Scientists found a huge crater under the ground, more than 180 kilometers wide and 20 kilometers deep. They discovered a special layer of rock all around the world with a rare element called iridium, which is common in space rocks but rare on Earth. This helped them prove that a giant meteor caused the crater. This impact is famous because it is linked to the extinction of the dinosaurs.

Where you see it in real life

• Chicxulub Crater, Mexico → The place where the biggest meteor hit and made a huge underground crater.
• Iridium layer in rocks → All over the world, a thin layer of iridium-rich clay marks the time of the impact.
• Extinction of dinosaurs → Most scientists believe this impact caused the sudden end of dinosaurs and many other species.
• Meteor showers → When you see shooting stars, these are tiny meteors burning up, but the Chicxulub meteor was millions of times bigger.
• Tunguska event (Russia, 1908) → A much smaller meteor exploded in the air, flattening trees over 2,000 square kilometers, but did not make a crater.
• Barringer Crater (Arizona, USA) → A smaller but visible crater made by a meteor about 50,000 years ago.

Why it matters

• Explains mass extinctions: The Chicxulub impact helps us understand why dinosaurs and many other species disappeared.
• Shows Earth's history: Studying craters tells us about Earth's past and how life changed.
• Warns us about future impacts: Knowing about big meteors helps scientists watch the sky and plan for possible dangers.
• Connects to space science: Learning about meteors links to planets, asteroids, and how our solar system formed.

Worked example

Let's see how big the Chicxulub meteor was:

Given: Diameter of meteor ≈ 10–15 km (about the size of a city)
Speed ≈ 20 km/s
Step 1: Find the energy released
Energy = ½ × mass × speed²
Step 2: Estimate mass (using average rock density and size)
Step 3: Calculate energy (it was about 100 million megatons of TNT)
Step 4: Compare: This is more than a billion times the energy of the Hiroshima bomb

Common mistakes

• Thinking all meteors are huge: Most meteors are tiny, like grains of sand, and burn up in the air.
• Confusing meteor, meteorite, and asteroid: A meteor is the flash in the sky, a meteorite is the rock that reaches the ground, and an asteroid is a space rock before entering the atmosphere.
• Believing dinosaurs were the only ones affected: Many plants and animals also went extinct after the impact.
• Assuming the crater is visible above ground: The Chicxulub crater is mostly buried under rock and water.

Remember it

The biggest meteor hit Mexico 66 million years ago, made a giant crater, and wiped out the dinosaurs.