Based on the fact sheets provided, the physical and chemical properties of Earth can be summarized as follows:
Physical Properties of Earth
- Shape and Size : Earth is an oblate spheroid, meaning it is slightly flattened at the poles and bulging at the equator. Its average diameter is about 12,742 km, with the equatorial diameter about 43 km longer than the polar diameter. The mean radius is approximately 6,371 km
- Mass and Density : Earth has a mass of about 5.97×10245.97\times 10^{24}5.97×1024 kg and an average density of 5.51 g/cm³, making it the densest planet in the Solar System
- Surface Composition : About 70% of Earth's surface is covered by water, with the rest being landmasses that are constantly changing due to plate tectonics
- Internal Structure : Earth has four main layers:
- Crust : The thin outer layer, varying from about 5-10 km thick under oceans to 10-70 km thick under continents, composed mainly of silicate rocks
* **Mantle** : Extends about 2,900 km below the crust, made mostly of silicate minerals rich in magnesium and iron; behaves as a solid but can flow plastically over geological time scales
* **Outer Core** : A liquid layer about 2,200 km thick, composed mainly of iron and nickel, responsible for Earth's magnetic field
* **Inner Core** : A solid sphere with a radius of about 1,220 km, composed primarily of iron and nickel, with temperatures up to 6,000 °C and extremely high pressure
- Heat and Temperature : Earth's internal heat comes from primordial heat and radioactive decay, with temperatures reaching up to 6,000 °C in the core. Heat is lost through mantle convection, plate tectonics, and conduction through the lithosphere
- Gravity and Orbital Characteristics : Earth has a surface gravity of about 9.807 m/s² and orbits the Sun at an average distance of approximately 149.6 million km, completing one orbit in about 365.25 days
Chemical Properties of Earth
- Composition by Mass :
- Iron: ~32.1%
- Oxygen: ~30.1%
- Silicon: ~15.1%
- Magnesium: ~13.9%
- Sulfur: ~2.9%
- Nickel: ~1.8%
- Calcium: ~1.5%
- Aluminium: ~1.4%
- Trace elements: ~1.2%
- Core Composition : The core is mostly iron (about 88.8%) with nickel (5.8%), sulfur (4.5%), and trace elements
- Crust Composition : The crust is dominated by oxides of silicon (silicates), aluminium, iron, calcium, magnesium, potassium, and sodium. Oceanic crust is mainly basaltic, and continental crust is granitic in composition
Summary
Earth is a dense, rocky planet with a layered internal structure consisting of a solid inner core, liquid outer core, viscous mantle, and solid crust. Its shape is an oblate spheroid due to rotation, and its surface is composed mostly of water and silicate rocks. The planet's internal heat drives mantle convection and plate tectonics, shaping the surface over time. Chemically, Earth is dominated by iron, oxygen, silicon, and magnesium, with a core rich in iron and nickel
