Cosmos: Science, Theories, and Celestial Bodies
Science and Technology
Science: A body of knowledge gained through observation and reasoning from which general principles and laws are deduced. Technology: A body of knowledge used to create objects and machines that adapt to the environment and meet our needs.
Scientific Literacy and Pseudoscience
Scientific literacy: A set of scientific expertise that exists. Individuals should possess basic scientific literacy to express themselves, form their own opinions, and avoid manipulation.
Pseudoscience: False science, such as astrology and parapsychology.
Serendipity in Science
Serendipity: Making fortunate and unexpected scientific discoveries; also known as chance in science.
The Universe
The universe encompasses everything that has existed, exists, and will exist in any place and on any terms. It consists of matter, energy, and cosmic voids, including interstellar matter, stars, and planets.
Big Bang and Big Crunch Theories
Big Bang Theory: Explains the origin of the universe, proposed and developed by George Lemaître and Gamow. It posits that energy transformed into matter, particles, and the simplest atoms. As the temperature decreased, these condensed to form nebulae, galaxies, stars, and planets.
Big Crunch Theory: If the expansion speed is greater than gravity, the universe expands. If speed equals gravity, movement slows, and the universe is balanced. If speed is less than gravity, movement slows, and the universe contracts, drawing galaxies together.
Components of the Universe
The universe consists of galaxies, which are composed of:
- Star systems
- Planets
- Nebulae: Huge clouds of cosmic dust and gas
- Interstellar matter
Galaxies and the Milky Way
Galaxies: Organizational units of the universe.
Milky Way: Belongs to the Local Group of galaxies, which is part of the Virgo Supercluster. Its length is 100,000 light years.
Nebulae and Stars
Nebulae: Large masses of gas and dust, serving as nurseries for stars. Examples include the Horsehead Nebula, the Eagle Nebula, and the Clock Nebula.
Stars: Large masses of gases at very high temperatures, emitting energy as radiation of all kinds. Their fuel is hydrogen, which undergoes thermonuclear fusion reactions. They release energy in various forms.
Asteroids, Meteorites, and Comets
Asteroids: Rocky bodies smaller than planets, orbiting the Sun within Neptune’s orbit.
Meteorites: The light phenomenon that occurs when a fragment of extraterrestrial matter enters the Earth’s atmosphere and disintegrates.
Comets: Celestial bodies made of ice and rock that orbit the Sun in highly elliptical paths.
Origin of the Solar System
Any theory about the origin of the solar system must explain the following:
- The Sun and planets revolve in the same direction.
- The planets travel in nearly circular orbits lying in the same plane.
- The rotation of most planets occurs in the same direction as their translation.
- The planets near the Sun are small and dense, while the outer planets are large and light.
- All planetary bodies show evidence of large impacts.
Planetesimals Theory
Planetesimals Theory: Conceived between 1944 and 1950, it proposes that the solar system formed about 4.5 billion years ago from gas and dust in a nebula located in the Milky Way.