- First Hypothesis: Comte de Buffon (French Scientist) – 1749 AD
1749 AD
First Hypothesis (Comte de Buffon)
- Monistic Concept / Parental Concept: Earth and planets originated from the Sun itself
- Dualistic Concept (Binary Concept): Earth and planets originated due to interaction between the Sun and another celestial body
⚡ Quick Recall
Monistic = one body (Sun alone) involved · Dualistic = two bodies involved
| Hypothesis | Proponent (Year) |
|---|
| Comet Hypothesis | Comte de Buffon (1749) |
| Astronomical Hypothesis | Immanuel Kant (1755) |
| Nebular Hypothesis | Laplace (1796) — later modified by T.J.J. See |
| Meteoroid Hypothesis | Lockyer (1890) |
| Planetary Hypothesis | T.C. Chamberlain (1905) |
⚠ Exam Trap
Laplace's Nebular Hypothesis (1796) was later modified by
T.J.J. See — a commonly misremembered name in MCQs.
| Hypothesis | Proponent (Year) |
|---|
| Tidal Hypothesis | James Jeans (1919) — modified by Jeffreys (1929) |
| Double Star Hypothesis | H.N. Russell (Henry Norris Russell) |
| Theory of Fission | George Darwin (1879) |
| Supernova Hypothesis | Prof. Fred Hoyle and Littleton (1939) |
| Interstellar Dust Hypothesis | Otto Schmidt (1943) |
⚡ Quick Recall
Tidal Hypothesis: Jeans (1919) → Modified by Jeffreys (1929)
- Age: 4.6 billion years
- Method of Determination: Radioactive Dating (1905 AD)
- Invented by Ernest Rutherford
| Dating Method | Key Details |
|---|
| Uranium Dating / Lead Dating / Radiometric Dating | Oldest rock • Most important in determining Earth's age |
| Potassium-Argon Method | — |
| Rubidium-Strontium Method | — |
| Uranium-Thorium Method | — |
| Radiocarbon Dating Method | — |
| Chlorine-36 Dating Method | — |
| Carbon Dating (C-14) | Latest rocks • Age determination of living beings / organic materials |
⚠ Exam Trap
Uranium/Lead Dating → used for the
oldest rocks (Earth's age); Carbon Dating (C-14) → used for
recent/organic material only — frequently interchanged in MCQs.
- Shape: Geoid or Flattened Ellipsoid
- Slightly flat at top and bottom
| Parameter | Details |
|---|
| Reason for Geoid Shape | Greater centrifugal force (at equator) → Bulging at centre • Gravitational force at the poles → Pull surface towards the centre |
| Earth's Mass | 5.97 × 10²⁴ Kg |
| Aquatic Part | 71% |
| Terrestrial Part | 29% |
⚡ Quick Recall
Earth is wider at the Equator and flatter at the poles — Geoid / Flattened (Oblate) Ellipsoid shape.
| Era / Event | Details |
|---|
| Origin period of Humans | Pliocene Epoch (First – African continent) |
| Era of Vertebrate Animals | Silurian Epoch |
| Era of Reptiles | Mesozoic Era |
| Age of Dinosaurs | Jurassic Epoch (180 million years ago from today) |
⚠ Exam Trap
Mesozoic Era is broadly known as the "Era of Reptiles," but the Jurassic Epoch within it specifically marks the "Age of Dinosaurs" — both facts get tested together.
| Fact | Details |
|---|
| First Hypothesis of Earth's Origin | Comte de Buffon – 1749 AD |
| Age of Earth | 4.6 billion years |
| Radioactive Dating – Invented by | Ernest Rutherford (1905 AD) |
| Most important dating method for Earth's age | Uranium / Lead / Radiometric Dating |
| Carbon Dating (C-14) used for | Latest rocks, living beings / organic materials |
| Shape of Earth | Geoid / Flattened Ellipsoid |
| Earth's Mass | 5.97 × 10²⁴ Kg |
| Aquatic vs Terrestrial Part | Aquatic – 71% • Terrestrial – 29% |
| Age of Dinosaurs | Jurassic Epoch – 180 million years ago |
| First humans appeared | Pliocene Epoch – African continent |
⚡ Quick Recall
Age of Earth (4.6 Bn yrs) = Age of Sun (4.6 Bn yrs) ≈ Age of Solar System (4.5 Bn yrs) — all formed together.