Complex sentence: In 2015 an object was discovered orbiting the Earth and designated by the Minor Planet Center as object, but it was soon found to be an accidental discovery of the Gaia spacecraft and the designation was retracted.
Split into simpler sentences: In 2015 an object was discovered orbiting the Earth and designated by the Minor Planet Center as object. It was soon found to be an accidental rediscovery of the Gaia spacecraft and the designation was retracted.