Astronomy Picture of the Day . Comet Borrelly's Nucleus . ... Credit Copyright: Deep Space 1 Team , JPL , NASA Explanation: What does a comet nucleus look like? ... Pictured above is the most detailed image ever taken of a comet nucleus, obtained Saturday by Deep Space 1 and released yesterday by NASA . ... Deep Space 1 images of Borrelly add welcomed bedrock to understanding Solar System history and to the accurate prediction of future brightness changes of notoriously fickle comet s. January . ...