Question: Who discovered Europa and Callisto?
SPARQL query: SELECT DISTINCT ?uri WHERE { <http://dbpedia.org/resource/Europa_(moon)> <http://dbpedia.org/property/discoverer> ?uri. <http://dbpedia.org/resource/Callisto_(moon)> <http://dbpedia.org/ontology/discoverer> ?uri}
Answer: The discoverer of both Europa and Callisto is [Galileo Galilei].