Place the following structures in order from largest to smallest:
galaxy, universe, planet, solar system

Explanation

To arrange the structures from largest to smallest, we can follow these steps:

1. **Identify the Largest Structure**:
- The largest structure in the universe is the **universe** itself. It encompasses everything, including all galaxies, stars, and planets.

2. **Identify the Next Largest Structure**:
- Within the universe, the next largest structure is a **galaxy**. A galaxy is a massive system that contains billions of stars, along with their planets, gas, dust, and dark matter.

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