Correct Option
The correct option is (a).
Explanation
The cosmos is organized in a hierarchical structure based on the scale and gravitational binding of celestial bodies, ranging from individual planetary bodies to the totality of space and time.Analysis of Hierarchy (Ascending Order):
- 1. Earth: Earth is a planet and a single celestial body. It represents the smallest unit among the provided options.
- 2. Solar System: The Solar System consists of the Sun, eight planets (including Earth), their satellites, asteroids, comets, and meteoroids. It is significantly larger than Earth but is a minor component of a galaxy.
- 4. Galaxy: A galaxy is a massive gravitationally bound system consisting of stars, stellar remnants, interstellar gas, dust, and dark matter. The Solar System is located within the Milky Way Galaxy, which contains billions of such star systems.
- 3. Universe: The Universe encompasses all of space, time, matter, and energy, including all galaxies and the vast voids between them. It is the largest entity in the hierarchy.
Therefore, the correct ascending order from smallest to largest is: Earth → Solar System → Galaxy → Universe (1 - 2 - 4 - 3).
Key Takeaway: The cosmic hierarchy expands progressively from individual planets to star systems (Solar System), to large collections of stars (Galaxies), and finally to the Universe, which contains all existence.