Behold: NGC 3199, aka the Banana nebula – a glowing cosmic cloud in the southern constellation of Carina, 12,000 light years away. To wit:
The nebula is about 75 light-years across in this narrowband, false-colour view. Though the deep image reveals a more or less complete bubble shape, it does look very lopsided with a much brighter edge along the top [the ‘banana’]. Near the centre is a Wolf-Rayet star, a massive, hot, short-lived star that generates an intense stellar wind. In fact, Wolf-Rayet stars are known to create nebulae with interesting shapes as their powerful winds sweep up surrounding interstellar material. In this case, the bright edge was thought to indicate a bow shock produced as the star plowed through a uniform medium, like a boat through water. But measurements have shown the star is not really moving directly toward the bright edge. So a more likely explanation is that the material surrounding the star is not uniform, but clumped and denser near the bright edge of windblown NGC 3199.