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. the universe and the earth 7th class pdf
While the universe contains trillions of planets, Earth is special. As a 7th-class student, you need to understand why Earth supports life. Slowly, oxygen filled the atmosphere
Earth is unique because it is at the perfect distance from the Sun to support life. What is the Universe? - NASA Science Finally, life could crawl onto land
A is a massive system of billions of stars, dust, and gas held together by gravity.
The Earth is not a perfect sphere. It is an – slightly flattened at the poles and bulging at the equator.
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.
