Our Earth — Flashcards

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The Big Bang theory states that the universe began approximately 13.7 billion years ago from a massive explosion. This theory explains how galaxies, stars, and planets were formed over billions of yea…

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The Geocentric theory, proposed by Ptolemy, suggested that Earth was at the center of the universe and all celestial bodies (Sun, Moon, planets, stars) revolved around it. This theory was widely accep…

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Geocentric Theory (Ptolemy): Earth at center, all celestial bodies revolve around Earth, accepted for thousands of years. Heliocentric Theory (Copernicus): Sun at center, Earth and other planets revol…

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Earth takes 365¼ days (one year) to complete one revolution around the Sun. It travels at a speed of 1,07,200 kilometers per hour. Earth's orbit is nearly circular, with distance ranging from 147 mill…

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Earth began as a ball of swirling dust and clouds. It passed through a molten stage due to heat from constant bombardment by space materials. Heavier substances sank to form the core, while lighter su…

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The outermost layer of Earth where we live, extending up to 100 km depth. It consists of various kinds of rocks and forms only 1% of Earth's volume. The crust is like the shell of an egg compared to E…

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1. Crust: 0-100 km (outermost layer, consists of rocks) 2. Mantle: 100-2,900 km (contains silicates, upper part is pliable) 3. Core: 2,900-6,376 km (made of iron and nickel, divided into liquid outer …

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The innermost layer of Earth (2,900-6,376 km depth), composed of dense materials like iron and nickel. It has two parts: Outer Core (2,900-5,100 km) - liquid metallic material; Inner Core (5,100-6,376…