- An animation from a planetary scientist and a geophysicist shows what Earth’s surface is made of – and just how much of it there is.
- Earth’s crust is up to 31 miles thick, but only makes up 0.49% of the entire planet.
- The mantle below is green. It’s not hot enough to glow red.
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Ever wonder what’s in the miles and miles of rocky crust just below your feet?
James O’Donoghue, a planetary scientist at the Japanese space agency (JAXA), asked himself that in 2019. So he sent a message to Dr. Christine Houser, a geophysicist and seismologist at Japan’s Earth-Life Science Institute. He had a vision: He wanted to illustrate the makeup of our planet’s crust to show just how thin its habitable surface really is.
“While there are a lot of animations showing a ball of Earth’s water above the planet, there hadn’t been any others to show the crust,” O’Donoghue told Business Insider in an email.
The video below is the result of the two scientists’ collaboration.
Though O’Donoghue is a planetary scientist, the information Houser shared surprised him.
“The mantle is green and I had no idea,” O’Donoghue said. “Even though it’s hot, it’s not enough to glow red hot.”
Sitting above the mantle, the Earth’s crust extends as far as 31 miles (50 kilometers) down on some parts of the planet, though it’s just 3 miles (5 kilometers) thick at the deepest points of the ocean. The crust is mostly silicon dioxide – also known as silica, a compound that makes up much of the world’s sand – and aluminium oxide.
All that material makes up only 0.49% of Earth’s mass.
“Remember Earth’s surface is the layer upon which every (known) living thing has ever lived,” O’Donoghue wrote on Twitter.
That thin layer of rock and water is also where earthquakes rumble and minerals are mined. For O’Donoghue, picking it apart was an exercise in perspective.
“My main takeaway was actually not so much about the compositions (I already roughly knew them), but in fact how big the spheres looked despite being only a tiny fraction of Earth’s mass,” O’Donoghue said. “I think other people were surprised at the lack of things like sodium and carbon, etc., which are common in our daily lives.”
Those elements do cycle through Earth’s surface, water, living beings, and atmosphere, but they make up a tiny fraction of its crust. In turn, all the life and minerals we know make up just a tiny fraction of the planet itself.
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