Free Republic

Explanation: What's that black spot on Jupiter? No one is sure. During one pass of NASA's Juno over Jupiter, the robotic spacecraft imaged an usually dark cloud feature informally dubbed the Abyss. Surrounding cloud patterns show the Abyss to be at the center of a vortex. Since dark features on Jupiter's atmosphere tend to run deeper than light features, the Abyss may really be the deep hole that it appears -- but without more evidence that remains conjecture. The Abyss is surrounded by a complex of meandering clouds and other swirling storm systems, some of which are topped by light...

Explanation: Saturn is bright in Earth's night skies. Telescopic views of the outer gas giant planet and its beautiful rings often make it a star at star parties. But this stunning view of Saturn's rings and night side just isn't possible from telescopes in the vicinity of planet Earth. Peering out from the inner Solar System they can only bring Saturn's day side into view. In fact, this image of Saturn's slender sunlit crescent with night's shadow cast across its broad and complex ring system was captured by the Cassini spacecraft. A robot spacecraft from planet Earth, Cassini called Saturn...

Explanation: Big, beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo but appears as only a faint smudge in the eyepiece of a small telescope. We see the disk of the nearby island universe tilted towards our line of sight in this remarkably deep and detailed galaxy portrait, a telescopic image that spans an area about the angular size of a full moon. In it, the giant galaxy's elongated yellowish core is dominated by the light from old, cool stars. Beyond...

Explanation: By starlight, this eerie visage shines in the dark with a crooked profile evoking its popular name, the Witch Head Nebula. In fact, this entrancing telescopic portrait gives the impression that a witch has fixed her gaze on Orion's bright supergiant star Rigel. More formally known as IC 2118, the Witch Head Nebula spans about 50 light-years and is composed of interstellar dust grains reflecting Rigel's starlight. The color of the Witch Head Nebula is caused not only by Rigel's intense blue light, but because the dust grains scatter blue light more efficiently than red. The same physical process...

Explanation: What created this huge space bubble? Blown by the wind from a star, this tantalizing, head-like apparition is cataloged as NGC 7635, but known simply as the Bubble Nebula. The featured striking view utilizes a long exposure to reveal the intricate details of this cosmic bubble and its environment. Although it looks delicate, the 10 light-year diameter bubble offers evidence of violent processes at work. Seen here above and right of the Bubble's center, a bright hot star is embedded in the nebula's reflecting dust. A fierce stellar wind and intense radiation from the star, which likely has a...

Explanation: The stars are destroying the pillars. More specifically, some of the newly formed stars in the image center are emitting light so energetic that is evaporating the gas and dust in the surrounding pillars. Simultaneously, the pillars themselves are still trying to form new stars. The whole setting is the star cluster NGC 602, and this new vista was taken by the Webb Space Telescope in multiple infrared colors. In comparison, a roll-over image shows the same star cluster in visible light, taken previously by the Hubble Space Telescope. NGC 602 is located near the perimeter of the Small...

Explanation: Sometimes a river of hot gas flows over your head. In this case the river created a Strong Thermal Emission Velocity Enhancement (STEVE) that glowed bright red, white, and pink. Details of how STEVEs work remain a topic of research, but recent evidence holds that their glow results from a fast-moving river of hot ions flowing over a hundred kilometers up in the Earth's atmosphere: the ionosphere. The more expansive dull red glow might be related to the flowing STEVE, but alternatively might be a Stable Auroral Red (SAR) arc, a more general heat-related glow. The featured picture, taken...

Explanation: What is the most spook-tacular nebula in the galaxy? One contender is LDN 43, which bears an astonishing resemblance to a vast cosmic bat flying amongst the stars on a dark Halloween night. Located about 1400 light years away in the constellation Ophiuchus, this molecular cloud is dense enough to block light not only from background stars, but from wisps of gas lit up by the nearby reflection nebula LBN 7. Far from being a harbinger of death, this 12-light year-long filament of gas and dust is actually a stellar nursery. Glowing with eerie light, the bat is lit...

Explanation: These brightly outlined flowing shapes look ghostly on a cosmic scale. A telescopic view toward the constellation Cassiopeia, the colorful skyscape features the swept-back, comet-shaped clouds IC 59 (left) and IC 63. About 600 light-years distant, the clouds aren't actually ghosts. They are slowly disappearing though, under the influence of energetic radiation from hot, luminous star gamma Cas. Gamma Cas is physically located only 3 to 4 light-years from the nebulae and lies just above the right edge of the frame. Slightly closer to gamma Cas, IC 63 is dominated by red H-alpha light emitted as hydrogen atoms ionized...

Explanation: Some 13,000 light-years away toward the southern constellation Pavo, the globular star cluster NGC 6752 roams the halo of our Milky Way galaxy. Over 10 billion years old, NGC 6752 follows clusters Omega Centauri, 47 Tucanae, and Messier 22 as the fourth brightest globular in planet Earth's night sky. It holds over 100 thousand stars in a sphere about 100 light-years in diameter. Telescopic explorations of NGC 6752 have found that a remarkable fraction of the stars near the cluster's core are multiple star systems. They also reveal the presence of blue straggle stars, stars which appear to be...

Explanation: A mere seven hundred light years from Earth toward the constellation Aquarius, a star is dying. The once sun-like star's last few thousand years have produced the Helix Nebula. Also known as NGC 7293, the cosmic Helix is a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution. Combining narrow band data from emission lines of hydrogen atoms in red and oxygen atoms in blue-green hues, this deep image shows tantalizing details of the Helix, including its bright inner region about 3 light-years across. The white dot at the Helix's center...

Explanation: What if a rocket could return to its launch tower -- and be caught? This happened for the first time 10 days ago, after a SpaceX Starship rocket blasted off from its pad in Boca Chica, Texas, USA. Starship then split, as planned, with its upper stage landing in the Pacific Ocean. The big difference was the lower stage, Super Heavy Booster 12, was caught by its launch tower about 7 minutes later. Catching a rocket for reuse is a new and innovative way to help reduce the cost of rocket flight by making rockets more easily reusable. Starship...

Explanation: These dark pillars may look destructive, but they are creating stars. This pillar-capturing picture of the Eagle Nebula combines visible light exposures taken with the Hubble Space Telescope with infrared images taken with the James Webb Space Telescope to highlight evaporating gaseous globules (EGGs) emerging from pillars of molecular hydrogen gas and dust. The giant pillars are light years in length and are so dense that interior gas contracts gravitationally to form stars. At each pillar's end, the intense radiation of bright young stars causes low density material to boil away, leaving stellar nurseries of dense EGGs exposed. The...

Explanation: The tails of Comet Tsuchinshan-ATLAS were a sight to behold. Pictured, C/2023 A3 (Tsuchinshan–ATLAS) was captured near peak impressiveness last week over the Eastern Sierra Mountains in California, USA. The comet not only showed a bright tail, but a distinct anti-tail pointing in nearly the opposite direction. The globular star cluster M5 can be seen on the right, far in the distance. As it approached, it was unclear if this crumbling iceberg would disintegrate completely as it warmed in the bright sunlight. In reality, the comet survived to become brighter than any star in the night (magnitude -4.9), but...

Explanation: 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 why visible matter is distributed as it is both in the local universe and on the cosmic microwave background. 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,...

Explanation: These six panels follow daily apparitions of comet C/2023 A3 Tsuchinshan-ATLAS as it moved away from our fair planet during the past week. The images were taken with the same camera and lens at the indicated dates and locations from California, planet Earth. At far right on October 12 the visitor from the distant Oort cloud was near its closest approach, some 70 million kilometers (about 4 light-minutes) away. Its bright coma and long dust tail were close on the sky to the setting Sun but still easy to spot against a bright western horizon. Over the following days,...

Explanation: On October 14 it was hard to capture a full view of Comet C/2023 A3 Tsuchinshan-ATLAS. Taken after the comet's closest approach to our fair planet, this evening skyview almost does though. With two telephoto frames combined, the image stretches about 26 degrees across the sky from top to bottom, looking west from Gates Pass, Tucson, Arizona. Comet watchers that night could even identify globular star cluster M5 and the faint apparition of periodic comet 13P Olbers near the long the path of Tsuchinshan-ATLAS's whitish dust tail above the bright comet's coma. Due to perspective as the Earth is...

Explanation: NASA's Europa Clipper is now headed toward an ocean world beyond Earth. The large spacecraft is tucked into the payload fairing atop the Falcon Heavy rocket in this photo, taken at Kennedy Space Center the day before the mission's successful October 14 launch. Europa Clipper's interplanetary voyage will first take it to Mars, then back to Earth, and then on to Jupiter on gravity assist trajectories that will allow it to enter orbit around Jupiter in April 2030. Once orbiting Jupiter, the spacecraft will fly past Europa 49 times, exploring a Jovian moon with a global subsurface ocean that...

Explanation: Sometimes the night sky is full of surprises. Take the sky over Lindis Pass, South Island, New Zealand one-night last week. Instead of a typically calm night sky filled with constant stars, a busy and dynamic night sky appeared. Suddenly visible were pervasive red aurora, green picket-fence aurora, a red SAR arc, a STEVE, a meteor, and the Moon. These outshone the center of our Milky Way Galaxy and both of its two satellite galaxies: the LMC and SMC. All of these were captured together on 28 exposures in five minutes, from which this panorama was composed. Auroras lit...

Explanation: How bright and strange will the tails of Comet Tsuchinshan-ATLAS become? The comet has brightened dramatically over the few weeks as it passed its closest to the Sun and, just three days ago, passed its closest to the Earth. C/2023 A3 (Tsuchinshan–ATLAS) became of the brightest comets of the past century over the past few days, but was unfortunately hard to see because it was so nearly superposed on the Sun. As the comet appears to move away from the Sun, it is becoming a remarkable sight -- but may soon begin to fade. The featured animated video shows...