NGC 5307: A Symmetric Planetary Nebula . ... Credit Copyright: H. Bond ( STScI ) R. Ciardullo ( Penn State ), WFPC2 , HST , NASA Explanation: Some stellar nebulae are strangely symmetric. For example, every major blob of gas visible on the upper left of NGC 5307 appears to have a counterpart on the lower right. ... NGC 5307 is an example of a planetary nebula with a spiral shape. ... NASA Web Site Statements, Warnings, and Disclaimers . NASA Official: Jay Norris. ...