From the University of Texas Libraries, "Review articles are an attempt by one or more writers to sum up the current state of the research on a particular topic. Ideally, the writer searches for everything relevant to the topic, and then sorts it all out into a coherent view of the “state of the art” as it now stands. Review Articles will teach you about:
the main people working in a field
recent major advances and discoveries
significant gaps in the research
ideas of where research might go next
Review Articles are virtual gold mines if you want to find out what the key articles are for a given topic. If you read and thoroughly digest a good review article, you should be able to “talk the talk” about a given topic. Unlike research articles, review articles are good places to get a basic idea about a topic."
Books are a core resource for understanding the foundation of astronomy topics, and you'll want to use Library Search as well as browsing the shelves of the astronomy collection to find books for your research.