The strange green glowing bubble shown below is a planetary nebula known as IC 1295. 
Planetary nebulas are gaseous regions of space surrounding a dying star. The star explodes and sends material flying from its core, which glows brightly because of the energy of the explosion.
The aging star is a blue-white dot at the center of the green bubble. It will slowly cool over the next few billion years, turning into a very faint white dwarf. By that point, the bubble will probably have dissipated.
This green bubble is located about 3,300 light-years away from us in the constellation Scutum, in our very own Milky Way galaxy.
It seems to have multiple shells of glowing gas — which are green because the gasses that came from the star contain a lot of oxygen.
Here's a video showing where in the Milky Way the nebula is located: