Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Explanation: The Horsehead Nebula is one of the most famous nebulae on the sky. It is visible as the dark indentation to the orange emission nebula at the far right of the featured picture. The horse-head feature is dark because it is really an opaque dust cloud that lies in front of the bright 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 orange color is caused by electrons recombining with protons to form hydrogen atoms. Toward the lower left of the image is the Flame Nebula, an orange-tinged nebula that also contains intricate filaments of dark dust. Two prominent reflection nebulas are visible: round IC 432 on the far left, and blueNGC 2023 just to the lower left of the Horsehead nebula. Each glows primarily by reflecting the light of their central star.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2021 November 2
SN Requiem: A Supernova Seen Three Times So Far
Image Credit: NASA, ESA, Hubble; Data: S. A. Rodney (U. South Carolina) et al.; Image Processing: J. DePasquale (STScI)Explanation: We’ve seen this same supernova three times — when will we see it a fourth? When a distant star explodes in a supernova, we’re lucky if we see it even once. In the case of AT 2016jka (“SN Requiem”), because the exploding star happened to be lined up behind the center of a galaxy cluster (MACS J0138 in this case), a comparison of Hubble Space Telescope images demonstrate that we saw it three times. These three supernova images are highlighted in circles near the bottom of the left frame taken in 2016. On the right frame, taken in 2019, the circles are empty because all three images of the single supernova had faded. Computer modeling of the cluster lens, however, indicates that a fourth image of the same supernova should eventually appear in the upper circle on the right image. But when? The best models predict this will happen in 2037, but this date is uncertain by about two years because of ambiguities in the mass distribution of the cluster lens and the brightness history of the stellar explosion. With refined predictions and vigilant monitoring, Earthlings living 16 years from now may be able to catch this fourth image — and perhaps learn more about both galaxy clusters and supernovas at once.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. (I think this is one of the coolest pictures NASA has shared with us this year.)
Explanation: The dream was to capture both the waterfall and the Milky Way together. Difficulties included finding a good camera location, artificially illuminating the waterfall and the surrounding valley effectively, capturing the entire scene with numerous foreground and background shots, worrying that fireflies would be too distracting, keeping the camera dry, and avoiding stepping on a poisonous snake. Behold the result — captured after midnight in mid-July and digitally stitched into a wide-angle panorama. The waterfall is the picturesque Zhulian waterfall in the Luoxiao Mountains in eastern Hunan Province, China. The central band of our Milky Way Galaxy crosses the sky and shows numerous dark dust filaments and colorful nebulas. Bright stars dot the sky — all residing in the nearby Milky Way — including the Summer Triangle with bright Vega visible above the Milky Way’s arch. After capturing all 78 component exposures for you to enjoy, the photographer and friends enjoyed the view themselves for the rest of the night.
Explanation: If you see this as a monster’s face, don’t panic. It’s only pareidolia, often experienced as the tendency to see faces in patterns of light and shadow. In fact, the startling visual scene is actually a 180 degree panorama of Northern Lights, digitally mirrored like inkblots on a folded piece of paper. Frames used to construct it were captured on a September night from the middle of a waterfall-crossing suspension bridge in Jamtland, Sweden. With geomagnetic storms triggered by recent solar activity, auroral displays could be very active at planet Earth’s high latitudes in the coming days. But if you see a monster’s face in your own neighborhood tomorrow night, it might just be Halloween.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Explanation: Spooky shapes seem to haunt this dusty expanse, drifting through the night in the royal constellation Cepheus. Of course, the shapes are cosmic dust clouds visible in dimly reflected starlight. Far from your own neighborhood, they lurk above the plane of the Milky Way at the edge of the Cepheus Flare molecular cloud complex some 1,200 light-years away. Over 2 light-years across and brighter than most of the other ghostly apparitions, vdB 141 or Sh2-136 is also known as the Ghost Nebula, seen at the right of the starry field of view. Inside the nebula are the telltale signs of dense cores collapsing in the early stages of star formation. With the eerie hue of dust reflecting bluish light from hot young stars of NGC 7023, the Iris Nebula stands out against the dark just left of center. In the broad telescopic frame, these fertile interstellar dust fields stretch almost seven full moons across the sky.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
The most distant object that most folks can see with the unaided eye is also the closest major galaxy to our own Milky Way. Although the Andromeda Galaxy lies a mind-bending 2.5 million light-years from Earth, its trillion stars are enough to emit a strong glow across the vast reaches of space. Despite the wide gap, the Milky Way and Andromeda are on a collision course and predicted to begin merging in roughly 4.5 billion years. (You’ve been warned.)
The Andromeda Galaxy was once thought to be a nebula. Early in the development of modern astronomy, any diffuse, undefined celestial body was called a ‘nebula,’ including what we now know to be a neighboring galaxy. Our modern definition of nebula refers to galaxies-in-training that will coalesce over cosmic time into something less…nebulous.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Explanation: Put on your red/blue glasses and float next to asteroid 101955 Bennu. Shaped like a spinning toy top with boulders littering its rough surface, the tiny Solar System world is about one Empire State Building (less than 500 meters) across. Frames used to construct this 3D anaglyph were taken by PolyCam on the OSIRIS_REx spacecraft on December 3, 2018 from a distance of about 80 kilometers. With a sample from the asteroid’s rocky surface on board, OSIRIS_REx departed Bennu’s vicinity this May and is now enroute to planet Earth. The robotic spacecraft is scheduled to return the sample to Earth in September 2023.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Explanation: Blown by fast winds from a hot, massive star, this cosmic bubble is huge. Cataloged as Sharpless 2-308 it lies some 5,000 light-years away toward the constellation of the Big Dog (Canis Major) and covers slightly more of the sky than a Full Moon. That corresponds to a diameter of 60 light-years at its estimated distance. The massive star that created the bubble, a Wolf-Rayet star, is the bright one near the center of the nebula. Wolf-Rayet stars have over 20 times the mass of the Sun and are thought to be in a brief, pre-supernova phase of massive star evolution. Fast winds from this Wolf-Rayet star create the bubble-shaped nebula as they sweep up slower moving material from an earlier phase of evolution. The windblown nebula has an age of about 70,000 years. Relatively faint emission captured by narrowband filters in the deep image is dominated by the glow of ionized oxygen atoms mapped to a blue hue. Presenting a mostly harmless outline, SH2-308 is also known as The Dolphin-head Nebula.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2021 October 17
The Einstein Cross Gravitational Lens
Image Credit & License: J. Rhoads (Arizona State U.) et al., WIYN, AURA, NOIRLab, NSFExplanation: Most galaxies have a single nucleus — does this galaxy have four? The strange answer leads astronomers to conclude that the nucleus of the surrounding galaxy is not even visible in this image. The central cloverleaf is rather light emitted from a background quasar. The gravitational field of the visible foreground galaxy breaks light from this distant quasar into four distinct images. The quasar must be properly aligned behind the center of a massive galaxy for a mirage like this to be evident. The general effect is known as gravitational lensing, and this specific case is known as the Einstein Cross. Stranger still, the images of the Einstein Cross vary in relative brightness, enhanced occasionally by the additional gravitational microlensing effect of specific stars in the foreground galaxy.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
NGC 289: Swirl in the Southern Sky
Image Credit & Copyright:Mike SelbyExplanation: About 70 million light-years distant, gorgeous spiral galaxy NGC 289 is larger than our own Milky Way. Seen nearly face-on, its bright core and colorful central disk give way to remarkably faint, bluish spiral arms. The extensive arms sweep well over 100 thousand light-years from the galaxy’s center. At the lower right in this sharp, telescopic galaxy portrait the main spiral arm seems to encounter a small, fuzzy elliptical companion galaxy interacting with enormous NGC 289. Of course spiky stars are in the foreground of the scene. They lie within the Milky Way toward the southern constellation Sculptor.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
NGC 7293: The Helix Nebula
Image Credit & Copyright:Ignacio Diaz BobilloExplanation: A mere seven hundred light years from Earth, toward the constellation Aquarius, a sun-like star is dying. Its last few thousand years have produced the Helix Nebula (NGC 7293), a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution. A total of 90 hours of exposure time have gone in to creating this expansive view of the nebula. Combining narrow band image data from emission lines of hydrogen atoms in red and oxygen atoms in blue-green hues, it shows remarkable details of the Helix’s brighter inner region about 3 light-years across. The white dot at the Helix’s center is this Planetary Nebula’s hot, central star. A simple looking nebula at first glance, the Helix is now understood to have a surprisingly complex geometry.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
NGC 7822: Cosmic Question Mark
Image Credit & Copyright: Yizhou ZhangExplanation: It may look like a huge cosmic question mark, but the big question really is how does the bright gas and dark dust tell this nebula’s history of star formation. At the edge of a giant molecular cloud toward the northern constellation Cepheus, the glowing star forming region NGC 7822 lies about 3,000 light-years away. Within the nebula, bright edges and dark shapes stand out in this colorful and detailed skyscape. The 9-panel mosaic, taken over 28 nights with a small telescope in Texas, includes data from narrowband filters, mapping emission from atomic oxygen, hydrogen, and sulfur into blue, green, and red hues. The emission line and color combination has become well-known as the Hubble palette. The atomic emission is powered by energetic radiation from the central hot stars. Their powerful winds and radiation sculpt and erode the denser pillar shapes and clear out a characteristic cavity light-years across the center of the natal cloud. Stars could still be forming inside the pillars by gravitational collapse but as the pillars are eroded away, any forming stars will ultimately be cut off from their reservoir of star stuff. This field of view spans over 40 light-years across at the estimated distance of NGC 7822.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
[I cannot get the video for today to copy anywhere that I can upload it from so instead here is a link that will take you to view it) From NASA.gov – Full Moon Silhouettes
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Explanation: This pretty starfield spans about three full moons (1.5 degrees) across the heroic northern constellation of Perseus. It holds the famous pair of open star clusters, h and Chi Persei. Also cataloged as NGC 869 (top) and NGC 884, both clusters are about 7,000 light-years away and contain stars much younger and hotter than the Sun. Separated by only a few hundred light-years, the clusters are both 13 million years young based on the ages of their individual stars, evidence that they were likely a product of the same star-forming region. Always a rewarding sight in binoculars, the Double Cluster is even visible to the unaided eye from dark locations. But a shroud of guitar strings was used to produce diffraction spikes on the colorful stars imaged in this
View our recorded Event Planning Webinar, and join the virtual Global Moon Party on October 9, for resources and activities that can take your International Observe the Moon Night to the next level.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
NGC 6559: East of the Lagoon
Image Credit & Copyright:Roberto SartoriExplanation: Slide your telescope just east of the Lagoon Nebula to find this alluring field of view in the rich starfields of the constellation Sagittarius toward the central Milky Way. Of course the Lagoon nebula is also known as M8, the eighth object listed in Charles Messier’s famous catalog of bright nebulae and star clusters. Close on the sky but slightly fainter than M8, this complex of nebulae was left out of Messier’s list though. It contains obscuring dust, striking red emission and blue reflection nebulae of star-forming region NGC 6559 at right. Like M8, NGC 6559 is located about 5,000 light-years away along the edge of a large molecular cloud. At that distance, this telescopic frame nearly 3 full moons wide would span about 130 light-years.
Image Credit & Copyright: Jari SaukkonenExplanation: Where do the dark streams of dust in the Orion Nebula originate? This part of the Orion Molecular CloudComplex, M43, is the often imaged but rarely mentioned neighbor of the more famous M42. M42, seen in part to the upper right, includes many bright stars from the Trapezium star cluster. M43 is itself a star forming region that displays intricately-laced streams of dark dust — although it is really composed mostly of glowing hydrogen gas. The entire Orion field is located about 1600 light years away. Opaque to visible light, the picturesque dark dust is created in the outer atmosphere of massive cool stars and expelled by strong outer winds of protons and electrons.
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