According to the data from NASA, the Earth’s vital statistics are as follows:
- Age: 4.543 billion years old
- Equatorial circumference: 40,075 km
- Equatorial radius: 6,378 km
- Polar radius: 6,356 km
- Total mass: 5.972 x 1024 kg
- Total volume: 1.08 x 1012 km3
- Total surface area: 5.10 x 108 km2
- Average density: 5.513 g/cm3
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- Earth Systems
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The Earth is composed of systems or “spheres”, each having their own unique properties, that continuously interact with one another. We can divide them into four major spheres
The atmosphere is a collective layer of gas that envelopes the Earth. It can be further divided into different layers based on characteristics.
The atmosphere is essential to life on Earth because (1) It shields the Earth and its inhabitants from harmful ultraviolet (UV) radiation from the Sun; (2) maintains the warmth of the Earth’s surface; and (3) contains all of the essential gasses needed to support life. More about the atmosphere will be covered later on.
The hydrosphere refers to the bodies of water consisting of freely flowing bodies of water found on the surface of the Earth, as well as water reservoirs stored below the ground as groundwater.
This sphere covers nearly 71% of the Earth’s surface.
Nearly 97.4% of the water in the hydrosphere is composed of saline or salt water found in vast oceans covering the Earth. The remaining 2.6% is made up of fresh water, mostly stored in glaciers and ice caps and underground reservoirs.
Although freshwater makes up only a tiny fraction of the total, we and other Earth residents rely on it for survival.
The biosphere refers to the narrow band on the Earth’s surface where all biological life resides. This could range from bustling cities, lush tropical rainforests, arid deserts, or even extreme environments like the bottom of the ocean floor.
The geosphere is the largest out of all the spheres— extending from the surface of the Earth down to its center. It is composed of external processes that we can observe on the surface and internal processes that happen deep within.
Here’s a fun fact: soil can be thought of as the interface of the four spheres. It is made up of weathered or broken down rock (geosphere), organic matter or humus (biosphere), moisture (hydrosphere), and air (atmosphere).
Next topic: The Layers of the Earth and its Composition
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