Cocoon Nebula Deep Field

Inside the Cocoon Nebula is a newly developing cluster of stars. The cosmic Cocoon on the upper right also punctuates a long trail of obscuring interstellar dust clouds to its left. Cataloged as IC 5146, the beautiful nebula is nearly 15 light-years wide, located some 3,300 light years away toward the northern constellation of the Swan (Cygnus). Like other star forming regions, it stands out in red, glowing, hydrogen gas excited by young, hot stars and blue, dust-reflected starlight at the edge of a nearly invisible molecular cloud. In fact, the bright star near the center of this nebula is likely only a few hundred thousand years old, powering the nebular glow as it slowly clears out a cavity in the molecular cloud’s star forming dust and gas. This exceptionally deep color view of the Cocoon Nebula traces tantalizing features within and surrounding the dusty stellar nursery. [via NASA]

Salt Pepper and Ice

There’s a “camera” comet now moving across the sky. Just a bit too dim to see with the unaided eye, Comet 21P / Giacobini-Zinner has developed a long tail that makes it a good sight for binoculars and sensitive cameras. The movement of the Comet 21P on the sky was captured last week in the featured time-lapse video compressing 90 minutes into about 2.5 seconds. What might seem odd is that the 21P’s tail is not following the comet’s movement. This is because comet tails always point away from the Sun, and the comet was not moving toward the Sun during the period photographed. Visible far in the background on the upper left is the Salt & Pepper star cluster, M37, while the bright red star V440 Auriga is visible just about the frame’s center. This 2-km ball of dust-shedding ice passed its nearest to the Sun and Earth only last week and is now fading as it crosses into southern skies. Comet 21P should remain visible, however, and photogenic to stabilized cameras, for another month or so. [via NASA]

Cosmic Collision Forges Galactic Ring

How could a galaxy become shaped like a ring? The rim of the blue galaxy pictured on the right is an immense ring-like structure 150,000 light years in diameter composed of newly formed, extremely bright, massive stars. That galaxy, AM 0644-741, is known as a ring galaxy and was caused by an immense galaxy collision. When galaxies collide, they pass through each other — their individual stars rarely come into contact. The ring-like shape is the result of the gravitational disruption caused by an entire small intruder galaxy passing through a large one. When this happens, interstellar gas and dust become condensed, causing a wave of star formation to move out from the impact point like a ripple across the surface of a pond. The likely intruder galaxy is on the left of this combined image from Hubble (visible) and Chandra (X-ray) space telescopes. X-ray light is shown in pink and depicts places where energetic black holes or neutron stars, likely formed shortly after the galaxy collision, reside. [via NASA]

Mont Blanc, Meteor, and Milky Way

Snowy Mont Blanc is near the center of this atmospheric night skyscape. But high, thin clouds fogged the skies at the photographer’s location, looking south toward Europe’s highest peak from the southern Swiss Alps. Still, the 13 second exposure finds the faint star fields and dark rifts of the Milky Way above the famous white mountain. Bloated by the mist, bright planet Saturn and Antares (right), alpha star of Scorpius, shine through the clouds to flank the galaxy’s central bulge. The high-altitude scene is from the rewarding night of August 12/13, so it also includes the green trail of a Perseid meteor shooting along the galactic plane. [via NASA]

Ice Halos at Yellowknife

You’ve probably seen a circle around the Sun before. More common than rainbows, ice halos, like a 22 degree circular halo for example, can be easy to spot, especially if you can shade your eyes from direct sunlight. Still it’s rare to see such a diverse range of ice halos, including sundogs, tangent, infralateral, and Parry arcs, all found in this snapshot from planet Earth. The picture was quickly taken in the late morning of September 4 from Yellowknife, Northwest Territories, Canada. The beautiful patterns are generated as sunlight (or moonlight) is reflected and refracted in six-sided water ice crystals in Earth’s atmosphere. Of course, atmospheric ice halos in the skies of other worlds are likely to be different. [via NASA]

Comet, Clusters, and Nebulae

Bright enough for binocular viewing Comet 21P / Giacobini-Zinner stands out, even in this deep telephoto mosaic of the star cluster and nebula rich constellation Auriga the Charioteer. On the night of September 9 its greenish coma and diffuse tail contrast with the colorful stars and reddish emission nebulae in the almost 10 degree field of view along the Milky Way. The comet was near its perihelion and closest approach to Earth, about 200 light-seconds away. Riding across the distant background just above the comet’s tail are well-known Auriga star clusters M38 (left of center) and M36 (toward the right) about 4,000 light-years away. At the top left, emission region IC 405 is only 1,500 light-years distant, more dramatically known as the Flaming Star Nebula. To its right lies IC 410, 12,000 light-years away and famous for its star-forming cosmic tadpoles. A child of our Solar System Giacobini-Zinner is a periodic comet orbiting the Sun once every 6.5 years, and the parent body of October’s Draconids meteor shower. [via NASA]


Our Moon’s appearance changes nightly. As the Moon orbits the Earth, the half illuminated by the Sun first becomes increasingly visible, then decreasingly visible. The featured video animates images taken by NASA’s Moon-orbiting Lunar Reconnaissance Orbiter to show all 12 lunations that appear this year, 2018. A single lunation describes one full cycle of our Moon, including all of its phases. A full lunation takes about 29.5 days, just under a month (moon-th). As each lunation progresses, sunlight reflects from the Moon at different angles, and so illuminates different features differently. During all of this, of course, the Moon always keeps the same face toward the Earth. What is less apparent night-to-night is that the Moon’s apparent size changes slightly, and that a slight wobble called a libration occurs as the Moon progresses along its elliptical orbit. [via NASA]

Milky Way over Trolls Tongue

You have to take a long hike to see the Troll’s Tongue — ten hours over rocky terrain. And in this case, it took three trips to capture the landform below a clear night sky. Trolltunga itself is a picturesque rock protrusion extending about 700 meters over mountainous cliffs near Lake Ringedalsvatnet in Norway. The overhang is made of billion-year-old Precambrian bedrock that was carved out by glaciers during an ice-age about 10,000 years ago. The featured picture is a composite of two exposures, a 15-second image of the foreground Earth followed 40 minutes later by an 87-second exposure of the background sky. Thousands of discernable stars dot the backdrop starscape in addition to billions of unresolved stars in the nearly vertical band of our Milky Way Galaxy. [via NASA]

Curiosity Vista from Vera Rubin Ridge

If you could stand on Mars — what might you see? If you were NASA’s Curiosity rover, just last month you would have seen the view from Vera Rubin Ridge, an intriguing rock-strewn perch on the side of Mount Sharp. In the featured 360-degree panorama, you can spin around and take in the vista from all directions, in many browsers, just by pointing or tilting. In this virtual reality view, many instruments on the rover are labelled, including antennas, the robotic arm, and the radioisotope thermoelectric generator (RTG). Dark sand and light rock cover the ground nearby in a mixture called lakebed mudstone. Towering Mount Sharp is only barely visible in the distance due to airborne dust from a planet-wide storm just winding down. Among its many discoveries, Curiosity has found that the raw ingredients for life are present on Mars. Next on Mars will be NASA’s Insight, on target to land in late November, which is scheduled to deploy a seismometer to better study the interior of the red planet. [via NASA]

M1: The Crab Nebula from Hubble

This is the mess that is left when a star explodes. The Crab Nebula, the result of a supernova seen in 1054 AD, is filled with mysterious filaments. The filaments are not only tremendously complex, but appear to have less mass than expelled in the original supernova and a higher speed than expected from a free explosion. The featured image, taken by the Hubble Space Telescope, is presented in three colors chosen for scientific interest. The Crab Nebula spans about 10 light-years. In the nebula’s very center lies a pulsar: a neutron star as massive as the Sun but with only the size of a small town. The Crab Pulsar rotates about 30 times each second. [via NASA]