Is it an insect? A strange fossil? An otherworldly eye, or even a walnut? No, it’s an intriguing kind of martian butterfly spotted by ESA’s Mars Express.
The Butterfly Nebula is one of those cosmic objects that demands our attention, and even our fascination. It's also known as NGC 6302 or the Bug Nebula, but whatever name we use, the stunning spectacle of ionized gases draws our human eyes in. In fact, Butterfly and its nebulae brethren may be more responsible for generating public enthusiasm in astronomy than any other type of object.

