Universe And The Earth 7th Class Pdf: The

Today, you live on a 4.5-billion-year-old planet. Your body is made of stardust—carbon from that ancient supernova. You are protected by a thin blue sky. Beneath your feet, a molten core churns. And above you, the universe continues to expand, filled with a hundred billion galaxies, each with a hundred billion stars.

At first, Earth was a nightmare: a molten ball of lava, constantly bombarded by comets and asteroids. It had no air, no water, just fire and rock. But over millions of years, Earth cooled. A thin, rocky crust formed on its surface. Heavier metals like iron and nickel sank to the center, creating a dense . Lighter rocks formed the thick mantle and the thin crust where we live. the universe and the earth 7th class pdf

Fast-forward billions of years to a quiet corner of a spiral galaxy we call the . A medium-sized, yellow star was born—our Sun . Around it swirled a disk of gas and dust. In this disk, tiny dust grains stuck together like snowballs, growing into pebbles, then boulders, then mountains, and finally planets. Today, you live on a 4

Slowly, oxygen filled the atmosphere. The sky turned blue. The ozone layer formed, shielding the land from the sun’s deadly ultraviolet rays. Finally, life could crawl onto land. Beneath your feet, a molten core churns

You can copy and paste this text into a PDF or a document to save as a PDF. Chapter 1: The Beginning of Everything