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With this last instrument he began a series of astronomical observations in October or November 1609 , discovering the satellites of Jupiter , hills and valleys on the Moon , the phases of Venus and observed spots on the sun ( using the projection method rather than direct observation ) .
 Jupiter, Moon, Venus
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:
 Jupiter, Moon, Venus