A possible sequence of events in the formation of the Earth: 1. The formation of planetesimals 2. The planetesimals become the...Read More >>A possible sequence of events in the formation of the Earth: 1. The formation of planetesimals 2. The planetesimals become the four rocky inner planets, Mercury, Venus, Earth and Mars. 3. Bombardment by meteorites causes the Earth’s rocky surface to melt. 4. Thousands of volcanic eruptions occur all over the globe. 5. The gases from these eruptions (and from collsions with planetesimals) collect to form the atmosphere. 6. Rain pours from the sky for millions of years, forming the oceans. Planet Earth is one of eight planets orbiting the Sun, one of billions of stars in the Milky Way Galaxy, itself one of billions of galaxies in the Universe. The Universe came into existence 13.7 billion years ago in an incredibly hot, dense explosion called the Big Bang. A few billion years later our Galaxy began to form, but it was not until about 4.6 billion years ago that the Sun and its family of planets, including the Earth, made their appearance.
The young Earth's changing landscape: 1. Bombardment by meteorites. 2. The Earth's rocky surface melts. 3. Gases burst into the...Read More >>The young Earth's changing landscape: 1. Bombardment by meteorites. 2. The Earth's rocky surface melts. 3. Gases burst into the sky through erupting volcanoes. 4. Ocean basins fill with water as a result of constant rains.
Formation of the Earth
A swirling disc of gas and dust, called a solar nebula, gradually merged into a dense ball of hot gas: the Sun. Spinning around this central furnace, particles of dust began to clump together, first into small fragments of rock, then large boulders. Over millions of years, some grew into blocks several kilometres across, called planetesimals. These, in turn started to collide with one another, building up like snowballs to become the four rocky inner planets, one of which was the Earth.
Planet Earth was once a global sea of extremely hot, molten rock.
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