Sonar is a technique used to find the distance between objects by sending sound waves and measuring the time they take to bounce back. it works well in water because sound waves travel efficiently in water. However, it is not suitable for measuring the distance between the earth and the moon for several reasons:

1. Distance: The distance between the earth and the moon is approximately 384,400 km (238,855 miles), which is much greater than the range of sonar technology. Sonar waves would have to travel through the vacuum of space, where there is no medium for sound waves to propagate.

2. Vacuum of Space: Space is a vacuum, meaning there is no air or any medium for sound waves to travel. Sound waves require a medium, such as air, water, or metal, to transmit their vibrations. In the vast emptiness of space, sound waves would simply dissipate without reaching the moon or bouncing back to Earth.

3. Speed of Sound: The speed of sound in air at room temperature is approximately 343 meters per second (1,235 kilometers per hour). In comparison, the speed of light is approximately 299,792,458 meters per second (1,079,252,848.8 kilometers per hour). Therefore, even if sound waves could travel through space, they would be much slower than light, making it impractical to use sonar for such long distances.

For measuring distances between celestial bodies like the Earth and the moon, techniques such as radar, laser ranging, and radio telescopes are employed. These methods utilize electromagnetic waves, which can travel through the vacuum of space and provide precise measurements of distances on astronomical scales.