Bipolar Planetary Nebula PN Hb 12 (IMAGE) ESA/Hubble Information Centre Caption This image shows an example of a bipolar planetary nebula known as PN Hb 12 -- popularly known as Hubble 12 -- in the constellation of Cassiopeia. The striking shape of this nebula, reminiscent of a butterfly or an hourglass, was formed as a Sun-like star approached the end of its life and puffed its outer layers into the surrounding space. For bipolar nebulae, this material is funnelled towards the poles of the ageing star, creating the distinctive double-lobed structure. Credit NASA, ESA Acknowledgement: Josh Barrington Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.