Do you need to get your students excited about learning earth history? Unfortunately, science can often seem boring to students, but we can show them just how fun science is by focusing on those facts that seem too crazy to be true.
5 Amazing Facts about Earth History
1. Earth’s rotation is slowing down.
When the Earth and Moon first formed 4.6 billion years ago, the Earth’s rotation was so fast that an entire day lasted just four hours. Scientists believe the Earth’s rotation is linked to the distance between the Earth and the Moon. The Moon was much closer to the Earth when it first formed, so Earth’s rotation was faster. As the Moon has moved away from the Earth, Earth’s rotation has slowed. When life first appeared on Earth 3.5 billion years ago, a day was about 12 hours long. When cyanobacteria started photosynthesizing 2.5 billion years ago, a day was 18 hours, and multicellular life didn’t appear until 1.2 billion years ago, when a day was 23 hours long. About 200 million years from now, the day will have stretched to 25 hours long.
Jose Luis Stephens/Shutterstock.com
Why is the Moon moving away from the Earth, and how is this affecting Earth’s rotation? My information text on tides explains everything!
2. Earth’s first eon is named after the Greek god of death.
Earth’s surface was so extreme during the first eon in earth history that scientists named it after Hades, the Greek god of death. The Hadean Eon lasted from Earth’s formation to about 4 billion years ago, but the oldest evidence of rocks puts them at 4.4 billion years ago. That means that for over 100 million years, the Earth was molten lava.
We have an iron core because of Earth’s liquid phase. The dense iron sunk to the middle of the Earth while the lighter silicates that make up our crust floated to the top.
3. Animals didn’t have eyes until 541 million years ago.
There has been life on Earth for 3.5 billion years, but life was simple and single-celled for most of that time. At the beginning of the Cambrian period, life got more complicated. Scientists call it the Cambrian Explosion, but it didn’t happen overnight. It took millions of years for life on Earth to change and spread. It just seems fast in the long timeline of Earth’s history.
One of the major developments of the Cambrian Explosion was the eyes. The first organisms to have eyes were trilobites, small marine arthropods that lived at the bottom of the ocean. They went extinct during the largest mass extinction event ever on Earth at the end of the Permian period. Still, as the first living organisms with eyes, they had a distinct advantage over other species.
Catmando/Shutterstock.com
4. The Tyrannosaurus rex lived closer to humans than the Stegosaurus in Earth history.
Dinosaurs dominated Earth for a long time. The earliest dinosaurs appear in the fossil record 245 million years ago during the Mesozoic Era. The Stegosaurus lived during the late Jurassic period between 156 and 144 million years ago. It was extinct long before Tyrannosaurus rex took over as the ultimate carnivore during the late Cretaceous period. The Tyrannosaurus rex went extinct with all of the other dinosaurs when a meteor struck Earth 65 million years ago. While the Stegosaurus, Tyrannosaurus rex, and humans are are millions of years apart, the Tyrannosaurus rex lived closer to us than the Stegosaurus.
metha1819/Shutterstock.com
5. Nine different species of humans lived together on Earth 30,000 years ago.
While only one human species exists on Earth today, 30,000 years ago, nine known human species were co-existing. Neanderthals lived in Europe, Denisovans lived in Asia, Homo erectus and Homo floresiensis lived in Indonesia, Homo rhodesiensis lived in Central Africa, Homo naledi lived in South Africa, and Homo luzonesis lived in the Philipines. By ten thousand years ago, there was only one species of human left. Homo sapiens from southern Africa had taken over the world.
There was no natural mass extinction event that took out the other human species, like the meteor that decimated the dinosaurs. Instead, scientists believe Homo sapiens were better at adapting to the environment. By ten thousand years ago, Homo sapiens were already developing agriculture as a permanent source of food and were just 1,000 years from the founding of Jericho, the first known city on Earth.
Teaching Earth History
Earth history is full of amazing facts like these! Your students will see that our history is alive, and we are learning more about where we come from every day as scientists study rock layers and discover new fossils. Our understanding of Earth history has radically changed just in the last 200 years. The word dinosaur didn’t even exist until 1841! Who knows what we will learn in the next two hundred years?
If you are teaching earth history in your middle school science class, but you need help, you can get my information texts on the different eons, eras, periods, and epochs of our past. Unlike middle school textbooks, I do not lump all of Earth’s early history into Precambrian Time. Instead, I share about the Hadean and Archean Eons. These eons are the foundation of where we are today!
Are You Teaching Another Science Topic?
I am working on creating more science units so that every science teacher can get exactly what he or she needs for her students. You can also read about how I use brain science to teach other science topics on my blog. Click the pictures below to learn more.
Coming soon!
Related Posts
