Universe History, Planet Formation, and Continental Drift
History of the Universe
1. Inflation
The universe expanded rapidly.
2. Formation of Matter
The universe was composed of subatomic particles bathed in a lot of energy called photons. When they cooled, they formed neutrons and protons.
3. First Atoms
Approximately 300,000 years after the Big Bang, hydrogen and helium atoms formed.
4. The Ignition of the Universe
Charged particles interfered with the photons. But, as atoms formed, light could travel freely through the newly created space. The universe became transparent, emitting cosmic background radiation.
5. The Formation of Stars and Galaxies
About 400 million years after the Big Bang, dense areas of space became centers of gravitational attraction, gathering matter to form nebulae, planets, and stars. Shortly after, galaxies were created.
6. Dark Energy
Around 9 billion years after the Big Bang, galaxies began to move at increasing speeds. It is believed that this is due to dark energy, a force of an unknown nature.
Conditions for Life on Planets
- The distance of the planet from the star
- Sufficient gravity on the planet
- A molten metal core
- The lifetime of the star
- The existence of nearby giant planets
- Location within the Milky Way
Seismic Waves
Seismic waves cross the inside of the planet and change direction and speed when they change the medium through which they propagate. S-waves do not propagate in fluids.
Wegener’s Theory
- All continents were once joined together to form a supercontinent called Pangea.
- Pangea fractured, and the fragments were displaced.
Evidence of Continental Drift
- Geographical: Wegener observed the limits of the continental shelves and thought that they had been united.
- Paleontological: Fossils have been found separated by thousands of miles. Research indicates that it is impossible for these animals to have crossed the ocean, suggesting that the continents were once united.
- Geological and Tectonic: If united in one continent, the chronology of rocks and mountain ranges form an almost continuous belt. For this reason, it was also thought that they were united.
- Paleoclimatic: These were the most important for Wegener. He found areas on Earth whose current climates did not match. Areas that were currently warmer were covered with ice in the past (India, Australia), while at the same time, North America and Europe had warm forests.
Origin of the Sun
A supernova explosion generated a shock wave close to a nebula, compressing it. In its center, the particles were closer and collided with one another. The center of the nebula heated, forming helium and releasing energy. This is how our sun was formed.
Formation of Planets
The nebula is compressed, collapses, and turns into a disk. Lighter elements are placed on the outside, where it is colder. In each area of the disk, a growing planet attracts matter closer to its zone of influence. With the excess material, satellites are formed. External giant planets are formed by gases. Interior planets, like Earth, consist of rock and metal.
The Big Bang
The Big Bang theory came from the Doppler effect, which discovered that galaxies were moving away from each other. The Big Bang was confirmed by radiation that came from all points of the universe.
Black Holes
These are concentrations of high-density material with a very large gravitational field. Not even light can escape. They are known by the radiation emitted by matter when accelerating, usually in the center of galaxies. The more bodies that fall in, the greater the mass and gravitational attraction. A safe distance is 7.7 million km.
Law of Gravitation
It states that bodies attract each other, the closer they are and the greater their mass.
Planets
- Mercury: It is the closest to the sun and the smallest, consisting of rocks and having no satellites.
- Venus: It is similar to Earth in mass and composition and has a greenhouse atmosphere.
- Earth: Life exists here. It formed at the same time as the sun, and the moon is its satellite.
- Mars: It resembles Earth but has a very tenuous atmosphere. It is the farthest from the sun of the four inner planets.
- Jupiter: It is the largest, gaseous, shines brightly, has more than 60 satellites, and is composed of hydrogen and helium.
- Saturn: It is a gas giant, and its rings are formed by gas.
- Uranus: It has an inclination of about 90° and has an atmosphere.
- Neptune: It is dynamic and gaseous.