In the beautiful landscapes of New Zealand, there’s a place called Milford Sound. Even though it’s called a “sound,” it’s actually a fjord. A fjord is a deep, narrow inlet of the sea between high cliffs, and it was formed by glaciers. Glaciers are huge, slow-moving sheets of ice that carved out the land over millions of years.
When you visit Milford Sound, you might start wondering, “How old is the Earth?” People have lots of different guesses. Some think it’s a few million years old, while others guess numbers like 2.3 million, 3 million, or even 40 billion years! But scientists have studied this a lot, and they agree that the Earth is about 4.5 billion years old. That’s a really big number, and it can be hard to imagine how long that is.
To help understand how long Earth’s history is, let’s use a fun example. Imagine that the entire history of the Earth is like the length of your outstretched arm:
Dinosaurs were around up to the second knuckle of your right middle finger. Humans have only been here at the very tip of that same finger! This shows how short human history is compared to the Earth’s long timeline of 4.5 billion years.
Milford Sound is not just a beautiful place; it also helps us think about how old the Earth is. By learning about the age of our planet and the timeline of life, we can better appreciate the amazing journey of evolution that has brought us to where we are today.
Imagine the entire history of Earth as a timeline stretching across your classroom. Use string and markers to represent major events like the formation of Earth, the appearance of life, and the rise of mammals. Work in groups to place these events accurately along the timeline, and discuss how short human history is compared to the Earth’s 4.5 billion years.
Using a tray of sand and water, simulate how glaciers carve out fjords like Milford Sound. Slowly move a block of ice over the sand to see how it creates a deep, narrow path. Discuss how glaciers have shaped landscapes over millions of years.
Explore the concept of large numbers by comparing the Earth’s age of 4.5 billion years to other big numbers. Calculate how many times your age fits into the Earth’s age, and express it in scientific notation. Discuss why understanding big numbers is important in science.
Use your own arm span to visualize Earth’s history. Mark key events on a strip of paper that matches your arm length, from the formation of Earth at one fingertip to the appearance of humans at the other. Share your timeline with classmates and discuss the significance of each event.
Write a creative story from the perspective of a glacier that helped form Milford Sound. Describe its journey over millions of years, carving out the landscape. Share your story with the class and discuss how glaciers have impacted Earth’s history.
Earth – The third planet from the Sun in our solar system, which is home to a diverse range of life forms and ecosystems. – Earth is the only known planet where life exists, thanks to its suitable atmosphere and water.
History – The study of past events, particularly in human affairs, but also includes the geological and biological past of Earth. – The history of Earth shows that it has undergone many changes, including the formation of mountains and the extinction of species.
Life – The condition that distinguishes living organisms from inorganic matter, including the capacity for growth, reproduction, and response to stimuli. – Scientists study the conditions necessary for life to understand how organisms survive in different environments.
Glaciers – Large masses of ice that form in cold regions and move slowly over land, shaping the landscape. – Glaciers have carved out valleys and fjords, leaving behind unique geological features.
Organisms – Living things, including plants, animals, fungi, and microorganisms, that have the ability to grow, reproduce, and maintain homeostasis. – All organisms, from the smallest bacteria to the largest whales, play a role in Earth’s ecosystems.
Evolution – The process by which different kinds of living organisms develop and diversify from earlier forms over generations. – The theory of evolution explains how species adapt to their environments over time.
Species – A group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. – Scientists discover new species every year, adding to our understanding of biodiversity.
Mammals – A class of warm-blooded vertebrate animals characterized by the presence of mammary glands, hair, and three middle ear bones. – Humans, whales, and elephants are all examples of mammals.
Dinosaurs – A group of reptiles that were the dominant terrestrial vertebrates for over 160 million years, until their extinction about 65 million years ago. – Fossils of dinosaurs help scientists learn about the Earth’s prehistoric past.
Sound – A type of energy that travels through the air or another medium as vibrations that can be heard when they reach a person’s or animal’s ear. – The sound of a volcano erupting can be heard from miles away, indicating its power.
