Explain briefly what causes the twinkling of stars at night?

Explanation

### Step-by-Step Solution:

1. **Understanding the Concept of Twinkling**:
- The twinkling of stars, also known as stellar scintillation, is a phenomenon observed when stars appear to change brightness and position slightly.

2. **Role of Atmospheric Refraction**:
- The primary cause of twinkling is the refraction of light. As the light from a star travels through the Earth's atmosphere, it passes through different layers of air that have varying temperatures and densities.

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