The History of The Universe
By: Haniah Virk and Isha Dixit
The Big Bang Theory
The Big Bang Theory was first created in the yer 1927 by Georges Lemaitre. According to the standard theory the Big Bang theory occurred around 13.7 billion years ago. Many people believe that the Big Bang was an explosion but some scientists like to explain it as an expansion of the universe.
Formation of the Sun
Around 5 billion years ago (almost 9 years after the Big Bang) the sun began to take form in our solar system. It began as a ball of gas (hydrogen and helium) and dust began to collect and over the course of 50 million years the pressure and temperature increased within the ball of gases and dust and eventually the ball of materials formed into the sun.
Formation of the Earth
The Earth was formed around 4.6 billion years ago by the same cloud of material that formed the sun. The rocky core was created first and the dense material of the planet sank towards the core and the lighter material was formed into the crust of the planet.
Formation of the Moon
A very popular theory of the moon forming is where scientists say that the Earth crashed with a large asteroid and a chunk of the Earth came off in its early years and began to orbit the Earth because of the gravitational pull of the Earth on the moon.
Formation of the First Cells
The first cells were formed on Earth around 3.7 million years ago. They are known as prokaryotic cells or cells without a true nucleus. These cells do not have a membrane around the nucleus and are found in organisms such as bacteria.
Oxygen Levels
Initially Earth didn't have much oxygen (also known as anoxic) but as cells began to form and as these cells began to form organisms such as plants and animals began to appear as well. When these plants appeared they began going through a process called photosynthesis which is what plants go through to create their food. As they do this they give out oxygen. This cause the oxygen levels on Earth to increase rapidly.
Cambrian Explosion
The Cambrian Explosion occurred around 535 million years ago. This "explosion" is referred to the time period where most of the animal phyla began to appear. They call it an explosion because one minute there were only a couple of animals and the next tons of animals begin to appear out of nowhere.
Evolution of Homo Sapiens
Humans belong to the species of homo sapiens. Homo sapiens began to evolve around 200,000 years ago. Many people say that homo sapiens began evolving in the continent of Africa. As they evolved they began to spread to different continents and pick up on different lifestyles.