The 2013 Hubble Space Telescope Advent Calendar

A yearly treat, at The Atlantic:  fantastic images, one each day, from the vast expanses of the universe, as seen through Hubble's eye.

It's time for my favorite holiday tradition: the 2013 Hubble Space Telescope Advent Calendar. Every day until Wednesday, December 25, this page will present an amazing new image of our universe from NASA's Hubble telescope. Be sure to bookmark this calendar and come back every day until Christmas, or follow on Twitter (@in_focus), Google+, Facebook, or Tumblr for daily updates. I hope you enjoy these amazing and awe-inspiring images and the efforts of the science teams who have brought them to Earth. Merry Christmas, and Peace on Earth to all. (Also, choosing the "1280px" viewing option below, if you can support it, is always a good option.) [25 photos (eventually)]

Here's the first image:

And its caption:

This year's first image: A composite image of visible-light observations by NASA's Hubble Space Telescope, combined with infrared data from the ground-based Large Binocular Telescope in Arizona to assemble a dramatic view of the well-known Ring Nebula. The Ring Nebula is the glowing remains of a Sun-like star, the smoldering core, called a white dwarf, is the tiny white dot in the center of the Nebula. The object is tilted toward Earth so that astronomers see the ring face-on. The Hubble observations reveal that the nebula's shape is more complicated than astronomers thought. The blue gas in the nebula's center is actually a football-shaped structure that pierces the red doughnut-shaped material. Hubble also uncovers the detailed structure of the dark, irregular knots of dense gas embedded along the inner rim of the ring. The faint, scallop-shaped material surrounding the ring was expelled by the star during the early stages of the planetary nebula formation. Most Sun-like stars become planetary nebulae at the end of their lives. Once a star consumes all of its hydrogen, the nuclear fuel that makes it shine, it expands to a red giant. The bloated star then expels its outer layers, exposing its hot core. Ultraviolet radiation from the core illuminates the discarded material, making it glow. The Ring Nebula is about 2,000 light-years away in the constellation Lyra. The nebula measures roughly one light-year across. (NASA, ESA, C.R. O'Dell, Vanderbilt University, and D. Thompson, Large Binocular Telescope Observatory)