Big Bang Cosmology, Planetary Science, and Solar Mechanics Notes on Earth Evolution

Proposed by George Lemaitre ($1929$) and defined in ($1932$).
Zero time to $10^{-6}$ seconds: All energy released from a small area via rapid expansion (Inflation). Fundamental forces (Gravitational, Electromagnetic, Strong, Weak) are formed. Quarks emerge as elementary building blocks at temperatures of $10^{13}$ degrees ($1000\,GeV$).
Immediately after $10^{-6}$ seconds: Universe expands to the size of the present solar system. Temperature cools to $10^{10}$ degrees ($1\,GeV$). Quark Hadron Transition occurs where quarks combine into protons and neutrons. Electrons exist as freely moving Leptons.
1 second to 3 minutes: Universe reaches $1000$ times current solar system size. Temperature reduces to $10^9$ degrees ($1\,MeV$). Primordial Nucleosynthesis occurs: Neutrons and Protons form atomic nuclei (Deuterium, Helium, and other elements).
3 minutes to $3\,\text{Lakh}$ years: Universe continues expanding and cooling. The Dark Era (Age of Universe) persists; high temperatures keep electrons free, trapping light particles (Photons) and making the universe opaque.
$300,000$ years post-Big Bang: Temperature cools to approx. $3000\,C$. Recombination and Decoupling occur as electrons are captured by photons to form Neutral Hydrogen. The universe becomes transparent and fills with light.

CMB: Also known as "Fossil Light" or "Primordial Light," it is the 1st light and afterglow of the Big Bang. It is invisible to the naked eye and observed through deep space telescopes like Planck, Gaia, Hubble, and James Webb.
Red Shift Phenomenon: Spectral analysis shows CMB wavelengths shifting toward the red end, demonstrating the Doppler Effect and proving the expansion of space.
Early Composition: Matter exists as Baryon (visible matter, $15\%$) and Dark Matter (unseen matter with gravitational effects, $85\%$).
First Stars: Megastars formed when initial "clots" reached $10 \times 10^6$ times the size of the present Sun. UV radiation from these stars ionized neutral hydrogen, ending the Dark Age.
Hubble's Law: Galaxies recede from Earth at speeds proportional to their distance.
Dark Energy: A mysterious energy responsible for the accelerated expansion of the universe.

Regions of infinite density ( $D \uparrow$ ), infinite gravity ( $G \uparrow$ ), and near-zero volume ( $V \downarrow$ ) formed by the collapse of megastars.
Chandrasekhar limit: Stars $1.44$ times the size of the Sun may collapse under their own weight once they run out of fuel.
Structures: Singularity (point of infinite density), Event Horizon (boundary where light cannot escape), and Accretionary disc (superheated gas and dust rotating at high velocity).
Notable Black Holes: GAIDA BH1 (nearest to Earth in Ophiucus constellation), TON 618 (supermassive), and SAGITARIUS A* (center of our galaxy).

IAU Criteria for Planets: Must orbit a star, have a spherical shape, and have cleared its orbital neighborhood. Pluto is reclassified as a Dwarf Planet.
Mercury: Closest to the Sun with no atmosphere and the highest diurnal temperature range ($-451\,F$ to $800\,F$).
Venus: Hottest planet due to a high $CO_2$ concentration causing a Runaway Greenhouse Effect.
Mars: The Red Planet (iron oxide). Contains Olympus Mons (largest volcano) and Valles Marineris (largest canyon).
Jupiter: Largest gaseous planet. Fast rotation ( $10\,\text{hours}$ ) causes Banding or Stratification of gases. The Great Red Spot is a $400$-year-old megastorm. Moons include Io, Callisto, Europa, and Ganymede (largest in the solar system).
Saturn: Least dense planet; would float on water. Cassini-Huygens is a major exploration mission. Rings of ice, gas, and dust disappear periodically due to Earth's line-of-sight alignment.
Uranus: Bluish color from cold Methane ($CH_4$). Coldest planet due to lack of primordial core heat. Rotates sideways at a $90^\circ$ angle and in retrograde fashion.
Neptune: Composed of $H, He, \text{and } CH_4$ . Features the Great Dark Spot megastorm and the moon Triton.
Outer Boundaries: The Kuiper Belt (icy objects) extends to the Heliopause, where solar winds balance interstellar influence. The Oort Cloud is a giant swarm of icy planetesimals and the origin of comets.

The Sun: Approximately $5 \times 10^9$ years old (middle-aged). Composed of Hydrogen and Helium in a plasma state, undergoing nuclear fusion ( $H \rightarrow He$ ).
Anatomy: Core (fusion center), Radiative Zone, Convective Zone (churning plasma), Photosphere (visible surface), Chromosphere, and Corona (outer atmosphere).
Solar Cycle: 11-year cycle where magnetic poles flip. Solar Maxima feature peak sunspots, CMEs (Coronal Mass Ejections), and auroras (Leh, Ladakh in $2024-25$).
NASA Parker Solar Probe: Mission to study the Corona, using a heat shield of Molybdenum Tetanium Zucconium and carbon composites. It discovered Alfven Waves responsible for heating the outer atmosphere.

L1 (Metastable): Positioned between Sun and Earth for advanced solar wind warnings. Used by ISRO's Aditya L1 and NASA's SOHO.
L2 (Metastable): Located in Earth's shadow zone. Ideal for deep space telescopes like James Webb and Hubble to observe CMB and distant galaxies.
L3 (Theoretical): Located behind the Sun; no data transfer possible.
L4 & L5 (Permanently Stable): Located at $60^\circ$ angles from Earth's orbit. Contain Trojian Asteroids, gas, and dust.

Formation: Earth formed $4.6 \times 10^9$ years ago. Primary and Secondary Density Differentiation created the core, mantle, and crust.
Theia Collision: A collision with a body $1/3$ the size of Earth formed the moon and tilted the Earth's axis.
Atmosphere/Hydrosphere: Primordial atmosphere (H, He) was lost to solar winds. Degassing released $H_2O$ vapor, $CO_2$, $SO_2$, and $CH_4$. Condensation of $H_2O$ created acidic oceans.
Great Oxygenation Event: Cyanobacteria (blue-green algae) evolved $3.8 \times 10^9$ years ago, using photosynthesis to consume $CO_2$ and release $O_2$. Photo dissociation eventually formed the Ozone ($O_3$) layer.

Asteroids: Rocky and metallic bodies primarily found in the Asteroid Belt between Mars and Jupiter.
Meteors: Streaks of light caused by dust and rock fragments entering Earth's atmosphere.
Comets: Composed of ice, rock, and gas. Sublimation causes a tail that always points away from the Sun due to solar winds. Hailey's comet returns every $76$ years.