Astronomers have used the NASA/ESA Hubble Space Telescope to image the tiny planetary nebula NGC 6886. These celestial objects signal the final death throes of mid-sized stars (up to about eight times the mass of the Sun); when such a star exhausts its supply of hydrogen fuel, the outer layers begin to expand and cool, which creates an envelope of gas and dust that shrouds the dying star. However, the star doesn’t go down without a fight, finding alternative ways to prevent it from collapsing under its own gravity and emerging as a white dwarf. In the process, the star’s surface temperature increases and it is eventually hot enough to emit strong ultraviolet radiation and make the cocoon of gas glow as a stunning planetary nebula.

Stellar death isn’t quick and painless: the planetary nebula stage typically lasts several tens of thousands of years. By studying the elements that are present in the nebula today, astronomers can determine the original chemical make-up of the star. Studies suggest that the star belonging to NGC 6886 may have originally been similar to the Sun, containing similar quantities of carbon, nitrogen and neon, although heavier elements, such as sulphur, were less plentiful.

Keen amateur astronomers with mid-level telescopes will find it a rewarding challenge to track down NGC 6886 in the small constellation of Sagitta. It is tiny, but not particularly faint: high magnification, a good chart, a dark site and averted vision are needed to spot this elusive celestial jewel.

This picture was created by combining images taken using the Wide Field Planetary Camera 2 on Hubble. Filters that let through emission from ionised nitrogen gas (F658N, coloured red), ionised oxygen (F502N, coloured blue) and a broadband yellow filter (F555W, coloured green, and also contributing to the blue) were used. The exposure times were 700 s, 600 s and 320 s respectively. The field of view is merely 30 arcseconds across.

Credit:

ABOUT THIS IMAGE:

Ground-based image of M13 taken with the NOAO Visitor’s Program 20-inch telescope at Kitt Peak National Observatory.

Object Names: M13, NGC 6205

Image Type: Astronomical

Credit: T. Bash, J. Fox, and A. Block/NOAO/AURA/NSF

The sands of time are running out for the central star of this the Hourglass Nebula. With its nuclear fuel exhausted, this brief, spectacular, closing phase of a sun-like star’s life occurs as its outer layers are ejected and its core becomes a cooling, fading white dwarf. In 1995, astronomers used the Hubble Space Telescope to make a series of images of planetary nebulae, including the one above. Here, delicate rings of colorful glowing gas (nitrogen-red, hydrogen-green, and oxygen-blue) outline the tenuous walls of the ‘hourglass.’ The unprecedented sharpness of Hubble’s images revealed surprising details of the nebula ejection process and may resolve the outstanding mystery of the variety of complex shapes and symmetries of planetary nebulae. Image Credit: NASA, WFPC2, HST, R. Sahai and J. Trauger (JPL)

Credit: ESA/Hubble & NASA 
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The image comprises one of the largest mosaics ever assembled from Hubble photos and includes observations taken by Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys. Hubble made the observations in October 2011. NASA and the Space Telescope Science Institute are releasing the image to celebrate Hubble’s 22nd anniversary. Credit: NASA, ESA, D. Lennon and E. Sabbi (ESA/STScI), J. Anderson, S. E. de Mink, R. van der Marel, T. Sohn, and N. Walborn (STScI), N. Bastian (Excellence Cluster, Munich), L. Bedin (INAF, Padua), E. Bressert (ESO), P. Crowther (University of Sheffield), A. de Koter (University of Amsterdam), C. Evans (UKATC/STFC, Edinburgh), A. Herrero (IAC, Tenerife), N. Langer (AifA, Bonn), I. Platais (JHU), and H. Sana (University of Amsterdam)

Several million young stars are vying for attention in a new NASA Hubble Space Telescope image of a raucous stellar breeding ground in 30 Doradus, a star-forming complex located in the heart of the Tarantula nebula.

The new image comprises one of the largest mosaics ever assembled from Hubble photos and includes observations taken by Hubble’s Wide Field Camera 3 and Advanced Camera for Surveys. NASA and the Space Telescope Science Institute (STScI) in Baltimore released the image today in celebration of Hubble’s 22nd anniversary.

“Hubble is the world’s premiere science instrument for making celestial observations, which allow us to unravel the mysteries of the universe,” said John Grunsfeld, associate administrator for NASA’s Science Mission Directorate in Washington and three-time Hubble repair astronaut. “In recognition of Hubble’s 22nd birthday, the new image of the 30 Doradus region, the birth place for new stars, is more than a fitting anniversary image.”

30 Doradus is the brightest star-forming region in our galactic neighborhood and home to the most massive stars ever seen. The nebula is 170,000 light-years away in the Large Magellanic Cloud, a small satellite galaxy of the Milky Way. No known star-forming region in our galaxy is as large or as prolific as 30 Doradus.

Collectively, the stars in the image are millions of times more massive than our sun. The image is roughly 650 light-years across and contains some rambunctious stars, including one of the fastest rotating stars and the highest velocity stars ever observed by astronomers.

The nebula is close enough to Earth that Hubble can resolve individual stars, giving astronomers important information about the stars’ birth and evolution. Many small galaxies have more spectacular starbursts, but the Large Magellanic Cloud’s 30 Doradus is one of the only star-forming regions that astronomers can study in detail. The star-birthing frenzy in 30 Doradus may be fueled partly by its close proximity to its companion galaxy, the Small Magellanic Cloud.

The image reveals the stages of star birth, from embryonic stars a few thousand years old and still wrapped in cocoons of dark gas, to behemoths that die young in supernova explosions. 30 Doradus churns out stars at a furious pace over millions of years. Hubble shows star clusters of various ages, from about 2 million to 25 million years old.

The region’s sparkling centerpiece is a giant, young star cluster named NGC 2070, only 2 million to 3 million years old. Its stellar inhabitants number roughly 500,000. The cluster is a hotbed for young, massive stars. Its dense core, known as R136, is packed with some of the heftiest stars found in the nearby universe, weighing more than 100 times the mass of our sun.

The massive stars are carving deep cavities in the surrounding material by unleashing a torrent of ultraviolet light, which is winnowing away the enveloping hydrogen gas cloud in which the stars were born. The image reveals a fantastic landscape of pillars, ridges and valleys. Besides sculpting the gaseous terrain, the brilliant stars may be triggering a successive generation of offspring. When the ultraviolet radiation hits dense walls of gas, it creates shocks, which may generate a new wave of star birth.

The image was made using 30 separate fields, 15 from each camera. Both cameras made these observations simultaneously in October 2011. The colors in the image represent the hot gas that dominates regions of the image. Red signifies hydrogen gas and blue represents oxygen.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center in Greenbelt, Md., manages the telescope. STScI conducts Hubble science operations. STScI is operated by the Association of Universities for Research in Astronomy, Inc., in Washington.

Enceladus, Saturn’s Moon

Below a darkened Enceladus, a plume of water ice is backlit in this view of one of Saturn’s most dramatic moons.

Dramatic plumes, both large and small, spray water ice from many locations along the moon’s famed “tiger stripes” near the south pole of Enceladus. The tiger stripes are fissures that spray icy particles, water vapor and organic compounds.

The terrain seen here is on the leading hemisphere of Enceladus (313 miles, or 504 kilometers across). North is up. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 20, 2012. The view was acquired at a distance of approximately 83,000 miles (134,000 kilometers) from Enceladus and at a Sun-Enceladus-spacecraft, or phase, angle of 165 degrees. Image scale is 2,628 feet (801 meters) per pixel.

Image credit: NASA/JPL-Caltech/Space Science Institute

Horizon

Flying at an altitude of about 240 miles over the eastern North Atlantic, the Expedition 30 crew aboard the International Space Station photographed this nighttime scene. This view looks northeastward. Center point coordinates are 46.8 degrees north latitude and 14.3 degrees west longitude. The night lights of the cities of Ireland, in the foreground, and the United Kingdom, in the back and to the right, are contrasted by the bright sunrise in the background. The greens and purples of the Aurora Borealis are seen along the rest of the horizon.

This image was taken on March 28, 2012.

Image Credit: NASA

Baby stars are creating chaos 1,500 light-years away in the cosmic cloud of the Orion Nebula. Four massive stars make up the bright yellow area in the center of this false-color image for NASA’s Spitzer Space Telescope. Green indicates hydrogen and sulfur gas in the nebula, which is a cocoon of gas and dust. Red and orange indicate carbon-rich molecules. Infant stars appear as yellow dots embedded in the nebula.

Image Credit: NASA

Apollo 13

NASA’s Apollo 13 was slated to be the United States’ third lunar landing mission. It launched April 11, 1970, at 2:13 p.m. EST from Launch Pad 39A in Florida. From left to right are mission commander Jim Lovell, command module pilot John Swigert and lunar module pilot Fred W. Haise. 

The mission was aborted after the service module oxygen tank ruptured. Still, the mission was classified as a “successful failure” because of the experience gained in rescuing the crew.

As the crew finished a 49-minute TV broadcast showing how comfortably they lived and worked in weightlessness on the evening of April 13, Lovell finished the interview stating, “This is the crew of Apollo 13 wishing everybody there a nice evening, and we’re just about ready to close out our inspection of Aquarius and get back for a pleasant evening in Odyssey. Good night.”

Nine minutes later, oxygen tank No. 2 blew up, causing the No. 1 tank to also fail. The command module’s normal supply of electricity, light and water was lost. The crew was about 200,000 miles from Earth.

After an intensive investigation, the Apollo 13 Accident Review Board identified the cause of the explosion. In 1965, the command mudule had undergone many improvements that included raising the permissible voltage to the heaters in the oxygen tanks from 28 to 65 volts DC. Unfortunately, the thermostatic switches on these heaters weren’t modified to suit the change. During one final test on the launch pad, the heaters were on for a long period of time. This subjected the wiring in the vicinity of the heaters to very high temperatures (1,000 degrees F), which were subsequently shown to have severely degraded the Teflon insulation. The thermostatic switches started to open while powered by 65 volts DC and were probably welded shut. Furthermore, other warning signs during testing went unheeded and the tank, damaged from eight hours of overheating, was a potential bomb the next time it was filled with oxygen. That bomb exploded on April 13, 1970 — 200,000 miles from Earth. 

The Apollo 13 crew safely landed in the Pacific on April 17, 1970.

Image Credit: NASA

Saturn from Frosty Drew Observatory on April 6, 2012.

Photo and caption by Andreas Koeberl

This shot was taken on Mauna Kea, Hawaii. It is the highest mountain on Earth when measured from its base in the ocean. Never in my life have I seen so many stars before! This place is truly amazing, breathtaking (literally) and mystical. The total exposure time for this picture was about 1.5 hours.

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Photo and caption by Brad Goldpaint

Double Arch, in southern Utah, was formed differently than most arches in the Arches National Park. It is what is known as a pothole arch, formed by water erosion from above rather than more typical erosion from the side. The larger opening has a span of 148 feet and a height of 104 feet. It lies atop an underground salt bed called the Paradox Formation, which is responsible for the arches. The visible rock formation is the salmon-colored entrada sandstone and the tan-colored Navajo sand.

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Share your own photos on National Geographic’s Your Shot, or rate your favorites, and the photo could appear on the National Geographic website, in the National Geographic Magazine or in future galleries here on Facebook. Visit Your Shot now:http://on.natgeo.com/yourshot