I really love this site and 
this is an awesome photo!
Kind of makes me realize how
small this planet Earth is....
Joe

Astronomy Picture of the Day

Explanation: Gorgeous spiral galaxy Messier 33 seems to have more than its fair share of glowing hydrogen gas. A prominent member of the local group of galaxies, M33 is also known as the Triangulum Galaxy and lies a mere 3 million light-years away. The galaxy's central 60,000 light-years or so are shown in this sharp galaxy portrait. The portrait features M33's reddish ionized hydrogen clouds or HII regions. Sprawling along loose spiral arms that wind toward the core, M33's giant HII regions are some of the largest known stellar nurseries, sites of the formation of short-lived but very massive stars. Intense ultraviolet radiation from the luminous, massive stars ionizes the surrounding hydrogen gas and ultimately produces the characteristic red glow. In this image, broadband data were combined with narrowband data recorded through a filter that transmits the light of the strongest visible hydrogen and oxygen emission lines.

Explanation: The interstellar cloud of dust and gas captured in this sharp telescopic snapshot is seen to change its appearance noticeably over periods as short as a few weeks. Discovered over 200 years ago and cataloged as NGC 2261, bright star R Monocerotis lies at the tip of the fan-shaped nebula. About one light-year across and 2500 light-years away, NGC 2261 was studied early last century by astronomer Edwin Hubble and the mysterious cosmic cloud is now more famous as Hubble's Variable Nebula. So what makes Hubble's nebula vary? NGC 2261 is composed of a dusty reflection nebula fanning out from the star R Monocerotis. The leading variability explanation holds that dense knots of obscuring dust pass close to R Mon and cast moving shadows across the dust clouds in the rest of Hubble's Variable Nebula.

Explanation: Vivid and lustrous, wafting iridescent waves of color wash across this skyscape from northern Sweden. Known as nacreous clouds or mother-of-pearl clouds, they are rare. But their unforgettable appearance was captured in this snapshot on January 12 with the Sun just below the local horizon. A type of polar stratospheric cloud, they form when unusually cold temperatures in the usually cloudless lower stratosphere form ice crystals. Still sunlit at altitudes of around 15 to 25 kilometers, the clouds diffract the sunlight even when the Sun itself is hidden from direct view.

Explanation: What's happening to Comet G3 ATLAS? After passing near the Sun in mid-January, the head of the comet has become dimmer and dimmer. By late January, Comet C/2024 G3 (ATLAS) had become a headless wonder -- even though it continued to show impressive tails after sunset in the skies of Earth's Southern Hemisphere. Pictured are images of Comet G3 ATLAS on successive January nights taken from Río Hurtado, Chile. Clearly, the comet's head is brighter and more centrally condensed on the earlier days (left) than on later days (right). A key reason is likely that the comet's nucleus of ice and rock, at the head's center, has fragmented. Comet G3 ATLAS passed well inside the orbit of planet Mercury when at its solar closest, a distance that where heat destroys many comets. Some of comet G3 ATLAS' scattering remains will continue to orbit the Sun.

Explanation: Some stars explode in slow motion. Rare, massive Wolf-Rayet stars are so tumultuous and hot that they are slowly disintegrating right before our telescopes. Glowing gas globs each typically over 30 times more massive than the Earth are being expelled by violent stellar winds. Wolf-Rayet star WR 124, visible near the featured image center, is thus creating the surrounding nebula known as M1-67, which spans six light years across. Details of why this star has been slowly blowing itself apart over the past 20,000 years remains a topic of research. WR 124 lies 15,000 light-years away towards the constellation of the Arrow (Sagitta). The fate of any given Wolf-Rayet star likely depends on how massive it is, but many are thought to end their lives with spectacular explosions such as supernovas or gamma-ray bursts.

Explanation: Yes, but can your rainbow do this? Late in the day, the Sun set as usual toward the west. However, on this day, the more interesting display was 180 degrees around -- toward the east. There, not only was a rainbow visible, but an impressive display of anticrepuscular rays from the rainbow's center. In the featured image from Lekeitio in northern Spain, the Sun is behind the camera. The rainbow resulted from sunlight reflecting back from falling rain. Anticrepuscular rays result from sunlight, blocked by some clouds, going all the way around the sky, overhead, and appearing to converge on the opposite horizon -- an optical illusion. Rainbows by themselves can be exciting to see, and anticrepuscular rays a rare treat, but capturing them both together is even more unusual -- and can look both serene and surreal.

2025 February 5

Explanation: Where is Comet ATLAS going? In the featured time-lapse video, the comet is not itself moving very much, but the Earth's rotation makes it appear to be setting over a hill. The Comet C/2024 G3 (ATLAS) sequence was captured with an ordinary camera on January 22 from the Araucanía Region in central Chile. Comet ATLAS has been an impressive site in the evening skies of Earth's Southern Hemisphere over the past few weeks, so bright and awe-inspiring that it may eventually become known as the Great Comet of 2025. Unfortunately, Comet G3 ATLAS is not going anywhere anymore because its central nucleus broke up during its close pass to the Sun last month. Some of the comet's scattered remains of rocks and ice will continue to orbit the Sun, some in nearly the same outward section of the orbit that the comet's nucleus would have taken.

Explanation: Grand spiral galaxies often seem to get all the glory, flaunting their young, bright, blue star clusters in beautiful, symmetric spiral arms. But small, irregular galaxies form stars too. In fact dwarf galaxy IC 2574 shows clear evidence of intense star forming activity in its telltale reddish regions of glowing hydrogen gas. Just as in spiral galaxies, the turbulent star-forming regions in IC 2574 are churned by stellar winds and supernova explosions spewing material into the galaxy's interstellar medium and triggering further star formation. A mere 12 million light-years distant, IC 2574 is part of the M81 group of galaxies, seen toward the northern constellation Ursa Major. Also known as Coddington's Nebula, the lovely island universe is about 50,000 light-years across, discovered by American astronomer Edwin Coddington in 1898.

Explanation: The giant galaxy cataloged as LEDA 1313424 is about two and a half times the size of our own Milky Way. Its remarkable appearance in this recently released Hubble Space Telescope image strongly suggests its nickname "The Bullseye Galaxy". Known as a collisional ring galaxy it has nine rings confirmed by telescopic observations, rippling from its center like waves from a pebble dropped into a pond. Of course, the pebble dropped into the Bullseye galaxy was a galaxy itself. Telescopic observations identify the blue dwarf galaxy at center-left as the likely collider, passing through the giant galaxy's center and forming concentric rings in the wake of their gravitational interaction. The Bullseye Galaxy lies some 567 million light-years away toward the constellation Pisces. At that distance, this stunning Hubble image would span about 530,000 light-years.

This warps my brain!

Explanation: A waxing crescent Moon and a waning crescent Venus are found at opposite corners of this twilight telephoto field of view. The close conjunction of the two brightest celestial beacons in planet Earth's western evening sky was captured on February 1 from Rosario, Argentina. On that date, the slender crescent Moon was about 3 days old. But the Moon's visible sunlit crescent will grow to a bright Full Moon by February 14. Like the Moon, Venus cycles through phases as it orbits the Sun. And while its visible sunlit crescent narrows, the inner planet's apparent size increases as it gets closer to Earth. In a Valentine from the Solar System, Venus, named for the Roman goddess of Love, will also reach its peak brightness in planet Earth's evening skies around February 14.

Explanation: What strange world is this? Earth. In the foreground of the featured image are the Pinnacles, unusual rock spires in Nambung National Park in Western Australia. Made of ancient sea shells (limestone), how these human-sized picturesque spires formed remains unknown. In the background, just past the end of the central Pinnacle, is a bright crescent Moon. The eerie glow around the Moon is mostly zodiacal light, sunlight reflected by dust grains orbiting between the planets in the Solar System. Arching across the top is the central band of our Milky Way Galaxy. Many famous stars and nebulas are also visible in the background night sky. The featured 29-panel panorama was taken and composed in 2015 September after detailed planning that involved the Moon, the rock spires, and their corresponding shadows. Even so, the strong zodiacal light was a pleasant surprise.

Explanation: Is this the largest hummingbird ever? Although it may look like a popular fluttering nectarivore, what is pictured is actually a beautifully detailed and colorful aurora, complete with rays reminiscent of feathers. This aurora was so bright that it was visible to the unaided eye during blue hour -- just after sunset when the sky appears a darkening blue. However, the aurora only looked like a hummingbird through a sensitive camera able to pick up faint glows. As reds typically occurring higher in the Earth's atmosphere than the greens, the real 3D shape of this aurora would likely appear unfamiliar. Auroras are created when an explosion on the Sun causes high energy particles to flow into the Earth's atmosphere and excite atoms and molecules of nitrogen and oxygen. The featured image was captured about two weeks ago above Lyngseidt, Norway.

Explanation: Will the spider ever catch the fly? Not if both are large emission nebulas toward the constellation of the Charioteer (Auriga). The spider-shaped gas cloud in the image center is actually an emission nebula labelled IC 417, while the smaller fly-shaped cloud on the left is dubbed NGC 1931 and is both an emission nebula and a reflection nebula. About 10,000 light-years distant, both nebulas harbor young star clusters. For scale, the more compact NGC 1931 (Fly) is about 10 light-years across. The featured deep image, captured over 20 hours during late January in Berkshire UK, also shows more diffuse and red-glowing interstellar gas and dust.

2025 February 12

Explanation: What can a space rock tell us about life on Earth? NASA's OSIRIS-REx spacecraft made a careful approach to the near-Earth asteroid 101955 Bennu in October of 2020 to collect surface samples. In September 2023, the robotic spaceship returned these samples to Earth. A recent analysis has shown, surprisingly, that the samples contained 14 out of the 20 known amino acids that are the essential building blocks of life. The presence of the amino acids re-introduces a big question: Could life have originated in space? However, the protein building blocks themselves held another surprise -- they contained an even mixture of left-handed and right-handed amino acids -- in contrast to our Earth which only has left-handed ones. This raises another big question: Why does life on Earth have only left-handed amino acids? Research on this is sure to continue.

Explanation: Riding high in the constellation of Auriga, beautiful, blue VdB 31 is the 31st object in Sidney van den Bergh's 1966 catalog of reflection nebulae. It shares this well-composed celestial still life with dark, obscuring clouds B26, B27, and B28, recorded in Edward E. Barnard's 1919 catalog of dark markings in the sky. All are these nebulae are interstellar dust clouds. Barnard's dark nebulae block the light from background stars. For VdB 31 the dust preferentially reflects bluish starlight from embedded, hot, variable star AB Aurigae. Exploring the environs of AB Aurigae with the Hubble Space Telescope has revealed the several million year young star is itself surrounded by a flattened dusty disk with evidence for the ongoing formation of a planetary system. AB Aurigae is about 470 light-years away. At that distance this cosmic canvas would span about eight light-years.

Explanation: The Rosette Nebula, NGC 2237, is not the only cosmic cloud of gas and dust to evoke the imagery of flowers, but it is probably the most famous. At the edge of a large molecular cloud in Monoceros some 5,000 light years away, the petals of this cosmic rose are actually a stellar nursery. The lovely, symmetric shape is sculpted by the winds and radiation from its central cluster of hot young, O-type stars. Stars in the energetic cluster, cataloged as NGC 2244, are only a few million years young, while the central cavity in the Rosette Nebula, is about 50 light-years in diameter. The nebula can be seen with a small telescope toward the constellation of Monoceros, the Unicorn. This natural appearing telescopic portrait of the Rosette Nebula was made using broadband color filters, but sometimes roses aren't red.

Explanation: Three suns seem to hug the horizon in this otherworldly winterscape. But the evocative scene was captured during a February 3rd snowmobile exploration of the mountainous region around Abisko National Park, northern Sweden, planet Earth. The two bright spots on either side of Earth's Sun are parhelia (singular parhelion), also known as mock suns or sun dogs. The parhelia are caused by hexagonal ice crystals suspended in the hazy atmosphere that reflect and refract sunlight. Commonly seen in winter and at high latitudes, the bright parhelia lie along the visible 22 degree ice halo of the Sun.

2025 February 16

Explanation: Here comes Jupiter. NASA's robotic spacecraft Juno is continuing on its highly elongated orbits around our Solar System's largest planet. The featured video is from perijove 11 in early 2018, the eleventh time Juno passed near Jupiter since it arrived in mid-2016. This time-lapse, color-enhanced movie covers about four hours and morphs between 36 JunoCam images. The video begins with Jupiter rising as Juno approaches from the north. As Juno reaches its closest view -- from about 3,500 kilometers over Jupiter's cloud tops -- the spacecraft captures the great planet in tremendous detail. Juno passes light zones and dark belts of clouds that circle the planet, as well as numerous swirling circular storms, many of which are larger than hurricanes on Earth. After the perijove, Jupiter recedes into the distance, then displaying the unusual clouds that appear over Jupiter's south. To get desired science data, Juno swoops so close to Jupiter that its instruments are exposed to very high levels of radiation.

Explanation: What's happened to the sky? Last Monday, the photogenic launch plume from a SpaceX rocket launch created quite a spectacle over parts of southern California and Arizona. Looking at times like a giant space fish, the impressive rocket launch from Vandenberg Air Force Base near Lompoc, California, was so bright because it was backlit by the setting Sun. The Falcon 9 rocket successfully delivered to low Earth orbit 23 Starlink communications satellites. The plume from the first stage is seen on the right, while the soaring upper stage rocket is seen at the apex of the plume toward the left. Venus appears at the top of the frame, while a bright streetlight shines on the far right. The featured image was captured toward the west after sunset from near Phoenix, Arizona.

Explanation: Seen as a seagull and a duck, these nebulae are not the only cosmic clouds to evoke images of flight. But both are winging their way across this broad celestial landscape, spanning almost 7 degrees across planet Earth's night sky toward the constellation of the Big Dog (Canis Major). The expansive Seagull (top center) is itself composed of two major cataloged emission nebulas. Brighter NGC 2327 forms the head with the more diffuse IC 2177 as the wings and body. Impressively, the Seagull's wingspan would correspond to about 250 light-years at the nebula's estimated distance of 3,800 light-years. At the lower right, the Duck appears much more compact and would span only about 50 light-years given its 15,000 light-year distance estimate. Blown by energetic winds from an extremely massive, hot star near its center, the Duck nebula is cataloged as NGC 2359. Of course, the Duck's thick body and winged appendages also lend it the slightly more dramatic popular moniker, Thor's Helmet.

Explanation: How do stars and planets form? New clues have been found in the protoplanetary system Herbig-Haro 30 by the James Webb Space Telescope in concert with Hubble and the Earth-bound ALMA. The observations show, among other things, that large dust grains are more concentrated into a central disk where they can form planets. The featured image from Webb shows many attributes of the active HH-30 system. Jets of particles are being expelled vertically, shown in red, while a dark dust-rich disk is seen across the center, blocking the light from the star or stars still forming there. Blue-reflecting dust is seen in a parabolic arc above and below the central disk, although why a tail appears on the lower left is currently unknown. Studying how planets form in HH 30 can help astronomers better understand how planets in our own Solar System once formed, including our Earth.

Explanation: Enormous elliptical galaxy Messier 87 is about 50 million light-years away. Also known as NGC 4486, the giant galaxy holds trillions of stars compared to the mere billions of stars in our large spiral Milky Way. M87 reigns as the large central elliptical galaxy in the Virgo galaxy cluster. An energetic jet from the giant galaxy's core is seen to stretch outward for about 5,000 light-years in this sharp optical and near-infrared view from the Hubble Space Telescope. In fact, the cosmic blow torch is seen across the electromagnetic spectrum from gamma-rays to radio wavelengths. Its ultimate power source is M87's central, supermassive black hole. An image of this monster in the middle of M87 has been captured by planet Earth's Event Horizon Telescope.