What is the radius of the moon?
1.74 x 106 m
Finding the Radius of the Moon
Let's determine the radius of the Moon. The radius of a celestial body like the Moon is the distance from its center to its surface. This is a fundamental physical property used in many astronomical calculations.
The question asks for the radius of the Moon and provides several options in scientific notation. We need to identify the correct value from the given choices.
The accepted average radius of the Moon is approximately 1,737.4 kilometers. To compare this with the options provided in meters, we need to convert kilometers to meters. Since 1 kilometer equals 1,000 meters ($\text{1 km} = \text{10}^3 \text{ m}$), we can make the conversion:
$\text{Radius of Moon (in meters)} \approx \text{1,737.4 km} \times \frac{\text{10}^3 \text{ m}}{\text{1 km}} = \text{1,737,400 m}$
Now, let's express this value in scientific notation to match the format of the options. Scientific notation writes a number as a product of a number between 1 and 10 and a power of 10. Moving the decimal point 6 places to the left from 1,737,400 gives us 1.7374. So, 1,737,400 meters is approximately $\text{1.7374} \times \text{10}^6 \text{ meters}$.
Let's compare this value to the given options:
| Option | Value | Comparison with $\approx \text{1.7374} \times \text{10}^6 \text{ m}$ |
|---|---|---|
| 1 | $\text{1.74} \times \text{10}^5 \text{ m}$ | This is $\text{174,000 m}$, which is too small ($\text{10}^5$ vs $\text{10}^6$). |
| 2 | $\text{1.79} \times \text{10}^6 \text{ m}$ | This is $\text{1,790,000 m}$. Close, but slightly larger than 1,737,400 m. |
| 3 | $\text{1.74} \times \text{10}^6 \text{ m}$ | This is $\text{1,740,000 m}$. This value is very close to 1,737,400 m and within reasonable approximation. |
| 4 | $\text{1.78} \times \text{10}^6 \text{ m}$ | This is $\text{1,780,000 m}$. Close, but not as close as option 3. |
Comparing the calculated value ($\approx \text{1.7374} \times \text{10}^6 \text{ m}$) with the options, the value $\text{1.74} \times \text{10}^6 \text{ m}$ is the closest approximation provided among the choices for the radius of the Moon.
Revision Table: Key Moon Radius Facts
| Concept | Detail |
|---|---|
| Moon's Average Radius (approx) | 1,737.4 km |
| Moon's Average Radius (in meters) | 1,737,400 m |
| Moon's Average Radius (Scientific Notation) | $\approx \text{1.7374} \times \text{10}^6 \text{ m}$ |
| Closest Option Provided | $\text{1.74} \times \text{10}^6 \text{ m}$ |
Additional Information about the Moon's Size
Understanding the radius helps us appreciate the size of the Moon. Here are some related points:
- The Moon is Earth's only natural satellite.
- Its radius is about one-quarter the radius of Earth. This means Earth's radius is roughly four times larger than the Moon's radius.
- The Moon's size affects its gravitational pull and its role in causing tides on Earth.
- Measurements of the Moon's radius are derived from various methods, including spacecraft missions and analysis of its shape (which is not a perfect sphere).
- The values presented are typically average values because celestial bodies can have slightly irregular shapes due to terrain variations (like mountains and valleys).
Knowing the radius of the Moon is essential for various calculations in astronomy and space science, such as determining its volume, surface area, or orbital characteristics.
Important Questions from Astronomy
What was the name of the first Indian satellite launched into the orbit?
Which is the nearest planet to the Sun?
Which of the following is called 'Black Beauty'?
A. Crow's name in Panchatantra
B. Petrol in raw form
C. Another name for Rapunzel
D. A coal-coloured stone from Mars
Which one of the following is not a constellation?
Which woman astronaut has set the record for the longest single spaceflight by a woman?
