Cosmos Unveiled: From Geocentric Views to Panspermia
1. Geocentric Model: The initial belief was that the Earth was the center of the universe, with the sun, moon, and stars revolving around it.
2. Copernicus and Galileo: Unlike the past, today we know the sun is the center of our solar system. Therefore, they would not be considered crazy for proposing a heliocentric model.
3. Determining Earth’s Age: The age of the Earth is determined by studying organic remains in rocks and fossils, which provide clues about its history over millions of years.
4. Scientific Theory: A scientific theory must be based on facts, explain observations, aid understanding, and be falsifiable, meaning it can be proven incorrect.
5. Solar System Formation: The solar system began with a nebula that contracted and rotated, forming a central mass (protosun) and a rotating disk. Nuclear fusion in the protosun marked the birth of a star. Dust and gas in the disk collided, forming protoplanets, which then accreted into planets.
6. Planetary Rotation: Not all planets rotate in the same direction. The gravitational attraction of the sun influences their rotation.
7. Pre-Copernican Heliocentric Theory: The heliocentric theory was born with Copernicus.
8. Astronomical Units and Light-Years: These units are used to measure vast distances in space, making it easier to express distances between planets and other celestial bodies.
9. Lunar Craters: The moon has more craters than Earth because it lacks an atmosphere, which protects Earth from many asteroid impacts.
10. Impact Craters on Jupiter and the Sun: Jupiter, being a gas planet, does not have impact craters. The sun’s surface temperature would melt any asteroid that collided with it.
11. Star and Shooting Star: A star is a celestial body that emits light, while a shooting star is a meteoroid that burns up in the atmosphere.
12. Miller-Urey Experiment: This experiment aimed to test the formation of organic molecules from inorganic matter. It showed that simple organic molecules could form from the components of the primitive atmosphere, leading to more complex molecules and coacervates, precursors to the first life forms.
13. Hydrothermal Vents and Prebiotic Synthesis: Hydrothermal vents may contribute to prebiotic synthesis, but life comes from pre-existing cells.
14. Hypotheses on the Origin of Life:
- Panspermia: The idea that the first organisms or their precursors originated elsewhere and traveled to Earth on asteroids or comets.
- Nebular Theory: The theory that the solar system formed from a rotating nebula.