Simplify the following text for a Grade 12 native English-speaking person.
Original: During an observation on March 25 , 1917 , 8 Flora was mistaken for the 15th magnitude star TU Leonis , which led to that star 's classification as a U Geminorum cataclysmic variable star .
Simplified: During an observation on March 25 , 1917 , 8 Flora was mistaken for the star TU Leonis , which led to that star 's classification as a U Geminorum cataclysmic variable star .