A light-year is how astronomers measure distance in space, hope this helps ^^
Global Positioning System (GPS)
Answer:
Water cycle, also called hydrologic cycle, cycle that involves the continuous circulation of water in the Earth-atmosphere system. Of the many processes involved in the water cycle, the most important are evaporation, transpiration, condensation, precipitation, and runoff.
Explanation:
The "medium" is the substance or material that carries a mechanical wave. One of the most important things to remember about waves is that they transport energy, not matter. This makes them different from other phenomenon in physics.
For simple definitions, visit the following website:
https://www.ducksters.com/science/physics/waves.php
