Question

Is the group of words a sentence or a run-on sentence?

Answer 1

a. Run-on

Example
Auroras illuminate the northern horizon, a greenish glow or sometimes a faint red one. 


A run-on is a phrase, statement or sentence of two or more independent clauses –clauses are independent phrases which has an subject and predicate and, can stand by its own self- that were conjoint or combined together regardless of punctuation. These are also called fused sentences.