The temperature of the sun is measured with

Options

A. Pyro-meter
B. Mercury thermometer
C. gas thermomemter
D. Both (1) and (2)

Answer

To solve the question regarding how the temperature of the Sun is measured, we will analyze the options provided and determine the correct answer step by step.

### Step 1: Understand the Measurement of Temperature
Temperature can be measured using various devices, but the method must be suitable for the conditions being measured. In the case of the Sun, which is extremely far away and emits thermal radiation, we need a device that can measure this radiation without direct contact.

### Step 2: Evaluate the Options
1. **Pyrometer**: A pyrometer is a non-contacting device that measures the thermal radiation emitted by an object. It is particularly useful for measuring high temperatures from a distance, making it suitable for measuring the temperature of the Sun.

2. **Mercury Thermometer**: A mercury thermometer relies on the expansion of mercury in a glass tube to measure temperature. However, it requires direct contact with the object being measured. Given the vast distance to the Sun, a mercury thermometer cannot be used.

3. **Gas Thermometer**: A gas thermometer measures temperature based on the pressure of a gas. While it is effective for measuring temperatures in controlled environments, it is not applicable for measuring the temperature of celestial bodies like the Sun.

### Step 3: Conclusion
Based on the analysis of the options:
- The **pyrometer** is the only suitable device for measuring the temperature of the Sun due to its ability to measure thermal radiation from a distance.
- The **mercury thermometer** and **gas thermometer** are not suitable for this purpose.

Thus, the correct answer is that the temperature of the Sun is measured with a **pyrometer**.