As a child or adult, one question that have definitely aroused in everyone's mind is "Is this universe infinite or it has some boundaries?" as a science or astronomy student this might be the first question to arouse in students mind. Coming back to the answer of this beautiful question- The observable universe is still huge but it has limits. This is because we know that the universe isn't infinitely old - we know that the big bang occured some 13.8 billion years ago. So from this we can conclude that the light has had only 13.8 billion years to travel and hence defines the limitations of universe. All we know or scientists believe is that universe is still far above from our observable distance but at some point it has limits for sure.
Nova is completely a new term for the beginners in the field of astronomical science. People usually call it as 'new star', but in actual nova is a transient astronomical event in which a sudden appearance of bright, appearantly new star takes place that slowly fades with time (usually several weeks or months). Nova has mainly 3 sub classes- classical nova recurrent nova dwarf nova Classical nova eruptions are the most common types of nova. The sudden rise or increase in the energy expels the atmosphere into interstellar space creating the envelope seen as visible light during the nova event. however they can be seen or appearing anywhere in the sky. Most of the nova are found telescopically, nearly one in every 1-2 year can be seen with naked eye visibility.