Which of the following is not catastrophic theory of origin of the earth?

Question

Accepted Answer

Option 3 is the correct answer because the Nebular Hypothesis of Laplace is an *evolutionary* theory of the origin of the Earth, not a *catastrophic* one.

Here's why:

*   **Nebular Hypothesis of Laplace:** This hypothesis proposes that the solar system formed from a rotating cloud of gas and dust (a nebula). Over time, this nebula contracted under its own gravity, flattened into a disk, and eventually formed the Sun at the center and planets from the remaining material in the disk. This is a gradual, evolutionary process, not a sudden, catastrophic event.

Now, let's explain why the other options are incorrect, focusing on why they *are* considered catastrophic:

*   **Planetessimal Hypothesis of Chamberlin and Moulton:** This hypothesis suggests that a star passed close to the Sun, drawing out material from it. This material then condensed into small bodies called planetesimals, which eventually accreted to form the planets. The close passage of another star is a significant, disruptive event, making it a catastrophic theory.

*   **Tidal Hypothesis of Jeans and Jeffreys:** Similar to the planetesimal hypothesis, this theory also involves a near collision or close passage of a star to the Sun. The gravitational interaction would have drawn out a tidal bulge from the Sun, which then separated and fragmented to form the planets. Again, the near collision is a catastrophic event.

*   **Nova Star Hypothesis of Hoyle and Lyttleton:** This hypothesis proposes that the solar system formed from the debris of a nova explosion (a star that suddenly increases greatly in brightness and then fades). The explosion of a star is, by definition, a catastrophic event.

Therefore, only the Nebular Hypothesis describes a gradual, evolutionary process, while the other three involve sudden, violent events, classifying them as catastrophic theories. This confirms that Option 3 is the correct answer.