If there were no atmosphere, Earth would have been

Options

A. slightly hotter
B. slightly cooler
C. very cool
D. very hot

Explanation

**Step-by-Step Solution:**

1. **Understanding the Role of the Atmosphere:**
- The Earth's atmosphere plays a crucial role in regulating temperature. It contains greenhouse gases that trap heat from the Sun.

2. **Sunlight and Infrared Rays:**
- The Sun emits various types of radiation, including infrared rays. These rays reach the Earth and are absorbed by the surface, warming it.

3. **Greenhouse Effect:**
- Normally, the infrared rays that are emitted from the Earth's surface are partially trapped by greenhouse gases in the atmosphere. This process is known as the greenhouse effect, which keeps the Earth's temperature at a level suitable for life.

4. **Consequences of No Atmosphere:**
- If there were no atmosphere, the infrared rays emitted by the Earth would not be trapped. Instead, they would escape back into space.

5. **Resulting Temperature:**
- Without the trapping of heat by the atmosphere, the Earth's surface would lose heat rapidly, leading to a significant drop in temperature.

6. **Conclusion:**
- Therefore, if there were no atmosphere, Earth would be extremely cold, making it inhospitable for life as we know it.

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