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Explanation: What's California doing in space? Drifting through the Orion Arm of the spiral Milky Way Galaxy, this cosmic cloud by chance echoes the outline of California on the west coast of the United States. Our own Sun also lies within the Milky Way's Orion Arm, only about 1,500 light-years from the California Nebula. Also known as NGC 1499, the classic emission nebula is around 100 light-years long. On the featured image, the most prominent glow of the California Nebula is the red light characteristic of hydrogen atoms recombining with long lost electrons, stripped away (ionized) by energetic starlight. The...

Explanation: The majestic Lagoon Nebula is filled with hot gas and the home for many young stars. Spanning 100 light years across while lying only about 5000 light years distant, the Lagoon Nebula is so big and bright that it can be seen without a telescope toward the constellation of the Archer (Sagittarius). Many bright stars are visible from NGC 6530, an open cluster that formed in the nebula only several million years ago. The greater nebula, also known as M8 and NGC 6523, is named "Lagoon" for the band of dust seen to the right of the open cluster's...

Explanation: The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the red emission nebula in the center of the above photograph. The horse-head feature is dark because it is really an opaque dust cloud that lies in front of the bright red emission nebula. Like clouds in Earth's atmosphere, this cosmic cloud has assumed a recognizable shape by chance. After many thousands of years, the internal motions of the cloud will surely alter its appearance. The emission nebula's red color is caused by electrons recombining with protons to...

Explanation: The constellation of Orion is much more than three stars in a row. It is a direction in space that is rich with impressive nebulas. To better appreciate this well-known swath of sky, an extremely long exposure was taken over many clear nights in 2013 and 2014. After 212 hours of camera time and an additional year of processing, the featured 1400-exposure collage spanning over 40 times the angular diameter of the Moon emerged. Of the many interesting details that have become visible, one that particularly draws the eye is Barnard's Loop, the bright red circular filament arcing down...

Explanation: Is star AE Aurigae on fire? No. Even though AE Aurigae is named the flaming star, the surrounding nebula IC 405 is named the Flaming Star Nebula, and the region appears to have the color of fire, there is no fire. Fire, typically defined as the rapid molecular acquisition of oxygen, happens only when sufficient oxygen is present and is not important in such high-energy, low-oxygen environments such as stars. The material that appears as smoke is mostly interstellar hydrogen, but does contain smoke-like dark filaments of carbon-rich dust grains. The bright star AE Aurigae, visible toward the right...

Explanation: The Great Nebula in Orion, also known as M42, is one of the most famous nebulas in the sky. The star forming region's glowing gas clouds and hot young stars are on the right in this sharp and colorful image that includes the bluish reflection nebulae NGC 1977 and friends on the left. Located at the edge of an otherwise invisible giant molecular cloud complex, these eye-catching nebulas represent only a small fraction of this galactic neighborhood's wealth of interstellar material. Within the well-studied stellar nursery, astronomers have also identified what appear to be numerous infant planetary systems. The...

Explanation: What's that in the sky? Although there was much to see in this spectacular panorama taken during the early morning hours of a day in late September, the brightest object in the sky was clearly the planet Venus. In the featured image, Venus was captured actually through a natural rock bridge, itself picturesque, in Spitzkoppe, Namibia. The planet, on the left of the opening, was complemented by a silhouette of the astrophotographer on the right. Above and beyond the rock bridge were many famous icons of a dark night sky, including, from left to right, the Pleiades star cluster,...

Explanation: Double, double toil and trouble; Fire burn, and cauldron bubble .... maybe Macbeth should have consulted the Witch Head Nebula. A frighteningly shaped reflection nebula, this cosmic crone is about 800 light-years away though. Its malevolent visage seems to glare toward nearby bright star Rigel in Orion, just off the right edge of this frame. More formally known as IC 2118, the interstellar cloud of dust and gas is nearly 70 light-years across, its dust grains reflecting Rigel's starlight. In this composite portrait, the nebula's color is caused not only by the star's intense bluish light but because the...

Explanation: This cosmic close-up looks deep inside the Soul Nebula. The dark and brooding dust clouds outlined by bright ridges of glowing gas are cataloged as IC 1871. About 25 light-years across, the telescopic field of view spans only a small part of the much larger Heart and Soul nebulae. At an estimated distance of 6,500 light-years the star-forming complex lies within the Perseus spiral arm of the Milky Way, seen in planet Earth's skies toward the constellation Cassiopeia. An example of triggered star formation, the dense star-forming clouds of IC 1871 are themselves sculpted by the intense winds and...

Explanation: What's that inside the Heart Nebula? First, the large emission nebula dubbed IC 1805 looks, in whole, like a human heart. The nebula glows brightly in red light emitted by its most prominent element: hydrogen. The red glow and the larger shape are all created by a small group of stars near the nebula's center. In the center of the Heart Nebula are young stars from the open star cluster Melotte 15 that are eroding away several picturesque dust pillars with their energetic light and winds. The open cluster of stars contains a few bright stars nearly 50 times...

On June 20, 1670, a new star appeared in the evening sky that gave 17th century astronomers pause. Eventually peaking out at +3rd magnitude, the ruddy new star in the modern day constellation of Vulpecula the Fox was visible for almost two years before vanishing from sight. The exact nature of Nova Vulpeculae 1670 has always remained a mystery. The event has often been described as a classic nova… but if it was indeed a garden variety recurrent nova in our own Milky Way galaxy, then why haven’t we seen further outbursts? And why did it stay so bright, for...

Explanation: The sands of time are running out for the central star of this hourglass-shaped planetary 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 - its core becoming a cooling, fading white dwarf. In 1995, astronomers used the Hubble Space Telescope (HST) 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 the HST images has revealed surprising details of...

Researchers have been able to map how the Eagle Nebula's Pillars of Creation are distributed in three-dimensional space for the first time, using new data from the Multi Unit Spectroscopic Explorer instrument on the European Southern Observatory's Very Large Telescope in Chile. Given the tremendous size of this section of the Eagle Nebula and its distance from Earth (around 7,000 light-years), researchers previously thought we were unlikely to ever see the shape of it in anything other than two flat dimensions, as in Hubble's famous photograph.

Explanation: Why isn't this ant a big sphere? Planetary nebula Mz3 is being cast off by a star similar to our Sun that is, surely, round. Why then would the gas that is streaming away create an ant-shaped nebula that is distinctly not round? Clues might include the high 1000-kilometer per second speed of the expelled gas, the light-year long length of the structure, and the magnetism of the star visible above at the nebula's center. One possible answer is that Mz3 is hiding a second, dimmer star that orbits close in to the bright star. A competing hypothesis holds...

As usual the MSM got it wrong: they’re all celebrating Hubble’s 25th birthday today when in fact it is the 25th anniversary of his launch into deep space. I should know, as Hub is my twin brother: I am a fraternal twin (female). My brother (Hub) is the mirror in the Hubble telescope. We are Cassegrain reflectors of Ritchey-Chretien design, and were conceived in 1979 at the Corning New York factory when 2 conjoined blanks of ultra-low expansion glass were sandwiched around a honeycomb lattice. (I didn’t mean to get into the sex stuff, but a lot of people are...

Explanation: Galactic or open star clusters are young. These swarms of stars are born together near the plane of the Milky Way, but their numbers steadily dwindle as cluster members are ejected by galactic tides and gravitational interactions. In fact, this bright open cluster, known as M46, is around 300 million years young. It still contains a few hundred stars within a span of 30 light-years or so. Located about 5,000 light-years away toward the constellation Puppis, M46 also seems to contain contradictions to its youthful status. In this pretty starscape, the colorful, circular patch above and right of the...

Explanation: It's stars versus dust in the Carina Nebula and the stars are winning. More precisely, the energetic light and winds from massive newly formed stars are evaporating and dispersing the dusty stellar nurseries in which they formed. Located in the Carina Nebula and known informally as Mystic Mountain, these pillar's appearance is dominated by the dark dust even though it is composed mostly of clear hydrogen gas. Dust pillars such as these are actually much thinner than air and only appear as mountains due to relatively small amounts of opaque interstellar dust. About 7,500 light-years distant, the featured image...

Explanation: Cradled in cosmic dust and glowing hydrogen, stellar nurseries in Orion the Hunter lie at the edge of giant molecular clouds some 1,500 light-years away. Spanning about 30 degrees, this breath-taking vista stretches across the well-known constellation from head to toe (left to right) and beyond. At 1,500 light years away, the Great Orion Nebula is the closest large star forming region, here visible just right and below center. To its left are the Horsehead Nebula, M78, and Orion's belt stars. Sliding your cursor over the picture will also find red giant Betelgeuse at the hunter's shoulder, bright blue...

Explanation: Near the outskirts of the Small Magellanic Cloud, a satellite galaxy some 200 thousand light-years distant, lies 5 million year young star cluster NGC 602. Surrounded by natal gas and dust, NGC 602 is just below center in this telescopic field of view with the angular size of the Full Moon on the sky. The cluster itself is about 200 light-years in diameter. Glowing interior ridges and swept back shapes strongly suggest that energetic radiation and shock waves from NGC 602's massive young stars have eroded the dusty material and triggered a progression of star formation moving away from...

Explanation: What dark structures arise from the Pelican Nebula? Visible as a bird-shaped nebula toward the constellation of a bird (Cygnus, the Swan), the Pelican Nebula is a place dotted with newly formed stars but fouled with dark dust. These smoke-sized dust grains formed in the cool atmospheres of young stars and were dispersed by stellar winds and explosions. Impressive Herbig-Haro jets are seen emitted by a star on the right that is helping to destroy the light year-long dust pillar that contains it. The featured image was scientifically-colored to emphasize light emitted by small amounts of ionized nitrogen, oxygen,...