Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: Jenna gave a report to her class about the Orion Nebula. She told the class that it was discovered in 1610. Which was most likely the topic of her paper?
Orion Nebula discovery.