Calendario dell’Avvento: 19 dicembre

In one of the largest and most detailed celestial images ever made, the coil-shaped Helix Nebula shows a fine web of filamentary “bicycle-spoke” features embedded in a colorful red and blue gas ring comprising one of the nearest planetary nebulae to Earth. Because the nebula is nearby, it appears as nearly one-half the diameter of the full Moon. The portrait offers a dizzying look down what is actually a trillion-mile-long tunnel of glowing gases. The fluorescing tube is pointed nearly directly at Earth, so it looks more like a bubble than a cylinder. A forest of thousands of comet-like filaments, embedded along the inner rim of the nebula, points back toward the central star, which is a small, super-hot white dwarf. (NASA, NOAO, ESA, the Hubble Helix Nebula Team, M. Meixner, STScI, and T.A. Rector, NRAO) More