Basically it means when something is moving in a line and is rotating in a larger system at the same time it appears to move. If you look it up online you can easily find a picture or two that should explain it pretty well.
Answer:
Explanation:
Biodiversity valuation of each species of natural resource
A complete value representing contribution to the system, usage (economically or ecologically), even carbon stock. Do, or could, nature areas keep databases of this information about their species?