NASA's Chandra X-ray Observatory has provided the first clear view of the faint boundary of the Crab Nebula's X-ray-emitting pulsar wind nebula. Powered by a central white pulsar, the nebula contains rapid rotation, a strong magnetic field that generates jets of matter and anti-matter, and an intense outward wind. This combination creates glowing filaments or "fingers and loops" of brightness that make the Crab Nebula so striking.

The inner X-ray ring is thought to be a shock wave marking the boundary between the surrounding nebula and the flow of matter and antimatter particles from the pulsar. Energetic electrons and positrons (antielectrons) move outward from this ring to brighten the outer ring and produce an extended X-ray glow. The fingers, loops, and bays in the image all indicate that the magnetic field of the nebula and filaments of cooler matter are controlling the motion of the electrons and positrons. The particles can move rapidly along the magnetic field and travel several light years before radiating away their energy. In contrast, they move much more slowly perpendicular to the magnetic field, and travel only a short distance before losing their energy. This effect can explain the long, thin, fingers and loops, as well as the sharp boundaries of the bays. The conspicuous dark bays on the lower right and left are likely due to the effects of a toroidal magnetic field that is a relic of the progenitor star. (Image credit: NASA/CXC/SAO/F.Seward)