“How the Earth was Formed” video notes Essay
“How the Earth was Formed” video notes
-sun was surrounded by a cloud of dust and gas
-as cloud cooled little grains of minerals started forming
-grains of minerals started bumping into each other
(Problem was nobody could explain how these microscopic minerals formed a planet) Then in 2003 astronaut Don Pettit performed an experiment onboard the international space station. He put some salt in a plastic bag and found that almost immediately the grains started gathering together into little clumps held together by static charge. -These mineral grains grew into small pieces of rock orbiting the sun -over the next few million years some of these rocks collided and grew bigger -when a rock grew to become around half a mile across, its gravitational pull became strong enough to pull objects towards it. (The bigger the rock was the faster it grew because it had higher gravitational pull) -so that biggest rock eventually grew to become ‘the fledgling earth’ -soon this small planet grew to attract even bigger objects that collided with its surface, every impact only served to increase its size. -The collisions were so intense it only (lol) took about 30 million years for the planet to grow to (approximately) its present size.
Presently, the earth is separated into three layers: A thin crust, then a massive dense layer of rock called the mantle, and an iron and nickel core. -So then this big rock became so hot that it melted and the denser materials drifted to the core while the lighter materials floated at the top -the heating up of fledgling earth could have been due to the incorporation of very hot radioactive elements. -The temperature of molten earth was now 2000 degrees, but at the edge of the planet the temperature of space was a constant -450 degrees, almost 2 ½ thousand degrees colder. -So because of this the surface could not stay molten forever -then in about a million years the earth had its thin crust, but volcanoes still erupted and meteorites still showered the surface Physicist Ernest Rutherford discovered that measuring radioactive decay could accurately measure the age of rocks. Soon after this rocks from around the globe were found to be billions of years old.
The meteor that hit in the crater in Arizona landed with the force of a two-mega ton atomic bomb. The explosion vaporized most of the meteorite, but individual fragments survive. Patterson took some samples, dated them, and found that they were around 4.5 billion years old. A recent study estimates the earth to be around 4 billion 567 million years old Theory of how the moon was formed: (1974) in the early solar system there were dozens of small planets chaotically orbiting the sun, one of them was on a collision course with earth. When it collided with the earth it blew some of its crustal/mantle rock off and within a few thousand years that debris formed the moon. (The other small planet was destroyed in the collision.) Rocks at Porpoise Cove in Canada are highly altered deformed volcanic lavas called amphibolite. They are 4.28 billion years old, 200 million years older than any rocks so far discovered and the closest anyone has come to earth’s original crust.
These amphibolites give us clues about the thickness of the earth’s early crust. O’Neill has found minerals that are unusual and can only form under high temperatures and pressures which proves that these rocks formed at least 12 miles into the crust of the earth, which tells us that just over 4 billion years ago the earth’s crust was about 12 miles thick. The chemical signature of amphibolite indicates that 4 billion years ago, earth had both a solid crust and oceans. (because amphibolite is similar to the ocean floor or something like that) Banded iron formations: made up of alternating light layers of silica and dark bands full of a mineral called magnetite. These bands full of magnetite only form underwater, further proving that oceans existed 4 billion years ago.
How water came to be on earth: Grains of table salt found in meteorites that fell to earth carry tiny droplets of water. Over the billions of years in which the earth was formed, these droplets added up and became the oceans, etc. 3.5 billion years ago there was no oxygen, the air was a mixture of sulfur, methane, carbon dioxide, and sulfuric acid. But primitive life forms did exist, the fossilized remains of coral like structures have been found in rocks that are of that age. They are called stromatolites. They are made up of billions of microbes called cyanobacteria, which produce oxygen. At this time oxygen was poisonous to other life forms, which used sulfur to obtain energy. Over time there was enough cyanobacteria to produce trillion of tons of oxygen, creating the atmosphere we breathe today. Over 100s of millions of years, decaying plant matter built up compressed layers, which eventually formed all the coal, oil, and gas deposits on the planet. Sedimentary rocks like limestone and chalk are largely made from the skeletons of marine animals, which accumulated at the bottom of shallow seas.