... Eris: More Massive than Pluto . ... Monitoring M2-9 . ... About 2,100 light-years away and over one light-year across, M2-9 is known as a twin jet or butterfly nebula in reference to its striking bipolar symmetry. ... Of course M96 is a spiral galaxy, and counting the faint arms extending beyond the brighter central region it spans 100 thousand light-years or so, about the size of our own Milky Way. vdB 152: Reflection Nebula in Cepheus . ... Reflection nebulas reflect light from a nearby star. ...