84386
It was the last natural satellite to be discovered by direct visual observation ; all later moons were discovered by photographic or digital imaging .
 natural satellite
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 natural satellite