ALT The Crab Nebula. An oval with complex structure extends from lower left to upper right against a black background. On the oval’s exterior lie curtains of glowing yellow and green fluffy material. Its interior shell shows large-scale loops of mottled filaments of yellow-white and green, studded with clumps and knots. Translucent thin ribbons of smoky blue lie within the remnant’s interior, brightest toward its center. The blue material follows different directions throughout, including sometimes sharply curving away from certain regions within the remnant. A faint, wispy ring of blue material encircles the very center of the nebula. Around and within the supernova remnant are many points of blue, green, purple, and white light.