It looks like a metal marble floating in space. Or the palantir of Orthanc, magically teleported from Middle Earth to 11,000 light years away, in the Cassiopeia constellation. But it's just a visual effect. This is the Bubble Nebula.
Cataloged as NGC 7635, it is also known simply as The Bubble Nebula. Although it looks delicate, the 10 light-year diameter bubble offers evidence of violent processes at work. Above and right of the Bubble's centre is a hot, O-type star, several hundred thousand times more luminous and approximately 45 times more massive than the Sun. A fierce stellar wind and intense radiation from that star has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud.