The is a fast-moving stream of
particles ejected into space.

people flirt to show their affection towards someone in a less forward way then telling. they want the other person to guess what they’re feeling to have the other person also start to like them

answer : a model is often used to explain and make things easier to understand when any scientific topic needs to be demonstrated and explained.

as in this case where a scientist wants to use a model to present the results of his detailed scientific investigation. he should do it as it will him to make the audience understand the concept in a much better way. also, it can be changed according to new scientific understandings.