Boston.com’s section The Big Picture has a lovely collection of images from the Hubble Space Telescope, presented in the form of an Advent Calendar by Alan Taylor, editor of the photo blog. Don’t miss the whole collection, but here are a few samples, with the descriptions taken from the site:
This object is a billowing tower of cold gas and dust rising from a stellar nursery called the Eagle Nebula. 7,000 light-years distant from us, the soaring tower is 9.5 light-years or about 90 trillion kilometers tall. Stars in the Eagle Nebula are born in clouds of cold hydrogen gas that reside in chaotic neighbourhoods, where energy from young stars sculpts fantasy-like landscapes in the gas. The tower may be a giant incubator for those newborn stars. A torrent of ultraviolet light from a band of massive, hot, young stars [off the top of the image] is eroding the pillar. The column is silhouetted against the background glow of more distant gas. The bumps and fingers of material in the center of the tower are examples of stellar birthing areas. These regions may look small but they are roughly the size of our solar system. The blue colour at the top is from glowing oxygen, the red color in the lower region is from glowing hydrogen. This image was taken in November 2004 with the Advanced Camera for Surveys (NASA, ESA, and The Hubble Heritage Team STScI/AURA) More (see this on Google Sky).
The “Retina Nebula” is in fact, a dying star named IC 4406. The left and right halves of the Hubble image are nearly mirror images of the other. If we could fly around IC 4406 in a starship, we would see that the gas and dust form a vast donut of material streaming outward from the dying star. From Earth, we are viewing the donut from the side. This side view allows us to see the intricate tendrils of dust that have been compared to the eye’s retina. Gas on the inside of the donut is ionized by light from the central star and glows brightly. Light from oxygen atoms is rendered blue in this image; hydrogen is shown as green, and nitrogen as red. One of the most interesting features here is the irregular lattice of dark lanes that criss-cross the center of the nebula. These lanes are about 24 billion kilometers wide, and are like an open mesh veil that has been wrapped around the bright donut. (NASA and The Hubble Heritage Team – STScI/AURA) More (see this on Google Sky).
Resembling a rippling pool illuminated by underwater lights, the Egg Nebula offers astronomers a special look at the normally invisible dust shells swaddling an aging star. These dust layers, extending over one-tenth of a light-year from the star, have an onionskin structure that forms concentric rings around the star. A thicker dust belt, running almost vertically through the image, blocks off light from the central star. Twin beams of light radiate from the hidden star and illuminate the pitch-black dust, like a shining flashlight in a smoky room. The Egg Nebula is located 3,000 light-years away in the constellation Cygnus. This image was taken with Hubble’s Advanced Camera for Surveys in September and October 2002. (NASA/ESA and The Hubble Heritage Team STScI/AURA) More (see this on Google Sky).
Enjoy (thanks to Zoë for alerting me to the site).