Impact in this case is a noun and refers to the force with which something strikes or hits something else. In this case, the impact of an asteroid created this well-preserved crater, located in Arizona, off Highway 40. (You can also enjoy this five-minute video narrative about asteroid impacts and listen to how the word is pronounced and used in context.)
This visual way of understanding the word "impact" can help you to imagine other meanings and uses of the word. For example, in the newspaper, editors choose their photos very carefully so that they have an impact on the reader. They want the image of an event to be memorable. They want it to be impactful.
Impactful is a relatively new adjective that has become quite common in reporting. It is quite controversial, however, and I am one who has never used the word. For a multi-page, thorough report on the origins of this word, you are invited to read this discussion. Also, please check out another fascinating blogpost regarding impactful by the linguist Anne Curzan. Then you can decide if you want to use it. As always, in building vocabulary, keep your eyes and ears open for the words you're trying to learn. Let me know if it's working for you.
