NASA Astronomy Picture of the Day:

The Great Nebula in Orion, an immense, nearby starbirth region, is one of the most famous of all astronomical nebulas. Here, glowing gas surrounds hot young stars at the edge of an immense interstellar molecular cloud only 1500 light-years away. In the featured deep image in assigned colors highlighted by emission in hydrogen, wisps and sheets of dust and gas are particularly evident. The Great Nebula in Orion can be found with the unaided eye near the easily identifiable belt of three stars in the popular constellation Orion. In addition to housing a bright open cluster of stars known as the Trapezium, the Orion Nebula contains many stellar nurseries. These nurseries contain much hydrogen gas, hot young stars, proplyds, and stellar jets spewing material at high speeds. Also known as M42, the Orion Nebula spans about 40 light years and is located in the same spiral arm of our Galaxy as the Sun.

Photo by Roberto Palaia

NASA Astronomy Picture of the Day:

Is our universe haunted? It might look that way on this dark matter map. The gravity of unseen dark matter is the leading explanation for why galaxies rotate so fast, why galaxies orbit clusters so fast, why gravitational lenses so strongly deflect light, and how visible matter is distributed. The featured image from the American Museum of Natural History's Hayden Planetarium Space Show, Dark Universe, highlights one example of how pervasive dark matter might haunt our universe. In this frame from a detailed computer simulation, complex filaments of dark matter, shown in black, are strewn about the universe like spider webs, while the relatively rare clumps of familiar baryonic matter are colored orange. These simulations are good statistical matches to astronomical observations. In what is perhaps a scarier turn of events, dark matter -- although quite strange and in an unknown form -- is no longer thought to be the strangest source of gravity in the universe. That honor now falls to dark energy, a more uniform source of repulsive gravity that seems to now dominate the expansion of the entire universe.

Photo by Tom Abel & Ralf Kaehler (KIPAC, SLAC), AMNH

NASA Astronomy Picture of the Day:

This Rosetta spacecraft selfie was snapped on October 7th, 2014. At the time the comet-chasing spacecraft was about 472 million kilometers from planet Earth, but only 16 kilometers from the surface of comet 67P/Churyumov-Gerasimenko. Looming beyond the spacecraft near the top of the frame, dust and gas stream away from the comet's curious double-lobed nucleus. Bright sunlight glints off one of Rosetta's 14 meter long solar arrays. In fact, two exposures, one short and one long, were combined to record the dramatic high contrast scene using the CIVA camera system on Rosetta's still-attached Philae lander. Its chosen primary landing site was on the visible hemisphere of the smaller lobe of the nucleus. This was the last image from Philae's camera before the lander separated from Rosetta on November 12. Shortly after separation Philae took another image looking back toward the orbiter and began its descent to the nucleus of the comet.

Photo by ESA/Rosetta/Philae/CIVA

NASA Astronomy Picture of the Day:

Looking toward the north from Mullion, New South Wales, Australia, the Andromeda Galaxy never gets more than a few degrees above the horizon. During the southern hemisphere spring, Andromeda is highest in the sky around midnight though. And in this telephoto scene from October 10/11, multiple exposures were used to reveal the spiral galaxy in tantalizing detail as it climbed above rolling Australian hills. Also known as M31, the Andromeda Galaxy is one of the brightest objects in the Messier catalog, but is only visible to the unaided eye as a small, faint, fuzzy patch. Digitally tracked and stacked frames were combined with a foreground shot in the deep astro-image composite to reveal the galaxy's greater extent in planet Earth's night. In the springtime night skyscape,the closest large spiral galaxy spans nearly 6 full moons.

Photo by Lucy Yunxi Hu

NASA Astronomy Picture of the Day:

Star light, star bright: is there a green star out tonight? Other than the Sun, all stars are so far from Earth that they appear as points in the sky. They are mostly white, but sometimes noticeably red or blue. This color typically relates to the temperature: blue stars are hotter than red stars. What about other colors? The featured image is an illustration showing WD J1330+6435, a white dwarf star, surrounded by an accretion disk with gas and rocks orbiting the star. White dwarfs are small, faint stars that are left over when a star like the Sun exhausts its nuclear fuel. Astronomers recently found that some white dwarf stars, despite their name, would appear yellow, green, cyan, pink, or purple. In these cases, trace elements that were accreted to these stars interact with the stellar atmosphere and shift its normally white color. But, alas! I wish I may, I wish I might, but they are too faint to see tonight...

Photo by Mark A. Garlick/University of Warwick

NASA Astronomy Picture of the Day:

Jinkies, look at all those ghosts! It took 100 hours of observation and a special oxygen filter for today’s image to capture three faint nebulas hidden in the Cassiopeia constellation. IC 59 and IC 63, the original Ghosts of Cassiopeia, haunt the region near multi-star system γ Cassiopeia. Energetic light from γ Cassiopeia causes the hydrogen gas in IC 59 and 63 to glow red. Their dust reflects and scatters some blue-ish white starlight. Newly discovered Objects 1, 2, and 3 appear as blue phantoms, revealing the presence of ionized oxygen. But ionized by what? Like at the bow of a speeding boat, γ Cassiopeia may be piling up material as the system moves through interstellar gas and dust. It follows that Object 3 may be the compressed and heated oxygen of that bow shock. Object 1 could be a planetary nebula if a central white dwarf is identified. The origins of these astronomical apparitions remain a mystery to be solved. Read here for more information on how you can help the observing team behind today's APOD.

Photo by Louis Leroux-Géré, Thibault Rouillée, Vincent Martin, Cédric de Decker (Starfront Observatories)

NASA Astronomy Picture of the Day:

This is an unusual rainbow. For one thing, the rainbow is not complete, appearing only in a sunlit fan -- but that by itself is not very unusual. What is most unusual is the fake location of the Sun. The Sun appears to be toward the front, just below those hills -- but it is not. That is not how rainbows work. Rainbows involve a backward reflection from falling rain, so that the Sun must really be behind you. In this case, gaps between clouds near the setting Sun allowed rays to cross the entire sky and appear to converge in front, an unusual phenomenon called anticrepuscular rays. The photo was taken with a phone last week at sunset in Presenzano, Italy. The seemingly reverse rainbow was noticed when hanging up laundry.

Photo by Aurelia Degli Esposti

NASA Astronomy Picture of the Day:

Explanation: What is Treble Clef? This unusual radio structure extends over 2 million light-years and resembles a common musical symbol -- but has its visible light hidden by our own Milky Way Galaxy. Examined in 2004, the nature of VLSS J0318.9+5755, dubbed Treble Clef, remained unknown. Recent observations by the Chandra X-ray Observatory and eROSITA, however, have led to the hypothesis that the Treble Clef central cloud of charged particles was originally expelled by a supermassive black hole at the center of a galaxy. After the radio emission from those particles faded, they may have been reinvigorated by a shock wave from the collision of two clusters of galaxies. The featured composite image shows radio emission in red, while recently discovered X-rays are shown in blue. Unusual objects like Treble Clef give humanity unexpected clues about how whole clusters of galaxies interact as well as the general evolution of our universe.

Photo by X-ray: NASA/CXC/INAF-IRA/A. Botteon et al.; Infrared: UKIDSS-GPS; Radio: ASTRONLOFAR; Image processing: NASA/CXC/SAO/N. Wolk

NASA Astronomy Picture of the Day:

Yes, but have you ever experienced the Eagle Nebula with your ears? The famous nebula M16 is best known for the feast it gives your eyes, highlighting bright young stars forming deep inside dark towering structures. These light-years long columns of cold gas and dust are some 6,500 light-years distant toward the constellation of the Serpent (Serpens). Sculpted and eroded by the energetic ultraviolet light and powerful winds from M16's cluster of massive stars, the cosmic pillars themselves are destined for destruction. But the turbulent environment of star formation within M16, whose spectacular details are captured in this combined Hubble (visible) and Chandra (X-ray) image, is likely similar to the environment that formed our own Sun. In the featured video, listen for stars and dust sounding off as the line of sonification moves left to right, with vertical position determining pitch.

Video by NASA, ESA, & The Hubble Heritage Project (STScI/AURA); Sonification: NASA, CXC, SAO, K. Arcand, M. Russo & A. Santaguida

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NASA Astronomy Picture of the Day:

Put on your red/blue glasses and float next to the jagged and double-lobed nucleus of Churyumov-Gerasimenko, also known as Comet 67P. The stereo anaglyph was created by combining two images from the Rosetta spacecraft's narrow angle OSIRIS camera taken on July 25, 2015 from a distance of 184 kilometers. Numerous jets are emanating from the small solar system world's active surface near its closest approach to the Sun. The larger lobe is around 4 kilometers in diameter, joined to a smaller, 2.5 kilometer diameter lobe by a narrow neck. Rosetta's mission to the comet ended in September 2016 when the spacecraft was commanded to a controlled impact with the comet's surface. Keep those 3D glasses on though. You can check out a catalog of nearly 1400 stereo anaglyphs created from Rosetta image data on this website.

Photo by ESA, Rosetta, MPS, OSIRIS - Stereo Anaglyph: Philippe Lamy and The Team

NASA Astronomy Picture of the Day:

Blasting into the predawn sky on Tuesday, October 13, a Falcon 9 rocket and Dragon spacecraft are headed for low Earth orbit in this stunning timelapse video captured from Indian Harbour Beach, Florida. Starting with a launch from Space Launch Complex 40 at Cape Canaveral Space Force Station, Falcon and Dragon are chasing the International Space Station on NASA's 35th Commercial Resupply Services mission. On cue, the space station itself enters the frame from the top. Almost 8 seconds into the 30 second timelapse. the bright streak of the ISS appears heading "down" toward the horizon. The first and second stages of the Falcon 9 are separating as the spectacular exhaust plume jellyfish grows, already catching the light of the rising Sun. The visible sequence of first stage boost back, re-entry, and landing burns begins around 20 seconds into the video. With the second stage following the ISS toward the distant horizon, the jellyfish plume continues to drift in the predawn sky, even after the successful first stage landing at planet Earth's Landing Zone 40.

Video by Eric Holland

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NASA Astronomy Picture of the Day:

The city lights outshine the stars in the City That Never Sleeps. Who would have thought that the Milky Way could be visible in this sky? This image was taken with a filter that blocks most visible light, capturing instead only light in the near-infrared region of the electromagnetic spectrum (with lower energy than visible light). The astrophotographer's clever setup blocks most of the light pollution from the city: old incandescent light bulbs and some neon lights are still bright in the near-infrared, but fluorescent and LED light bulbs are not. Of course, stars are also bright in the near-infrared! This image is a reminder that we all live under the same sky, and astronomy allows all of us to learn more about humanity's place in the Cosmos.

Photo by Jason Kurth, Ty Buckley