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: Bright sunlight glints as long dark shadows mark this image of the surface of the Moon. It was taken on July 20, 1969, by Apollo 11 astronaut Neil Armstrong, the first to walk on the lunar surface. Pictured is the mission's lunar module, the Eagle, and spacesuited lunar module pilot Buzz Aldrin. Aldrin is unfurling a long sheet of foil also known as the Solar Wind Composition Experiment. Exposed facing the Sun, the foil trapped particles streaming outward in the solar wind, catching a sample of material from the Sun itself. Along with 22 kilograms of moon rocks and lunar soil samples, the solar wind collector was returned for analysis in earthbound laboratories.

Explanation: Early spring in the northern hemisphere is good season for aurora hunters. Near an equinox Earth's magnetic field is oriented to favor interactions with the solar wind that trigger the alluring glow of the northern lights. On March 28/29 the skies over Kaunispää Hill, Lapland, Finland did not disappoint. That night's expansive auroral curtains are captured in this striking panoramic view that covers a full 360 degrees. Local skywatchers were mesmerized by bright displays lasted throughout the dark hours, shimmering with colors easily visible to the naked eye.

Explanation: The hydrogen in your body and present in every molecule of water came from the Big Bang. There are no other appreciable sources of hydrogen in the universe. The carbon in your body was made by nuclear fusion in the interior of stars, as was the oxygen. Much of the iron in your body was made during supernovas of stars that occurred long ago and far away. The gold in your jewelry was likely made from neutron stars during collisions that may have been visible as short-duration gamma-ray bursts or gravitational wave events. Elements like phosphorus and copper are present in our bodies in only small amounts but are essential to the functioning of all known life. The featured periodic table is color coded to indicate humanity's best guess as to the nuclear origin of all known elements. The sites of nuclear creation of some elements, such as copper, are not really well known and are continuing topics of observational and computational research.

Explanation: There was something behind the clouds. Upon close inspection, it was the Moon, which was hard to see yesterday around noon above the small village of Cessy, France. But soon, it was not only the Moon. As expected, a bright dot suddenly appeared from behind the Moon -- the planet Venus far in the distance. Captured in the single featured exposure, both appeared to show a crescent phase. The Moon's crescent was quite slight -- with only about 10 percent of its face illuminated by the Sun. In contrast, Venus's crescent was more full -- showing about 25 percent illumination. Venus appeared brighter because it is nearer the Sun and because its clouds are more reflective than the dark lunar surface. An occultation of Venus by the Moon is visible to only about 10 percent of the Earth, but in yesterday's event even most of that was experiencing daytime.

Explanation: Sometimes where Hubble finds darkness, Webb sees light. An example is today’s composite images of Messier 64 (M64), a nearby spiral galaxy of many names. The dark band of dust partially blocking its bright core earned it the moniker “the Black Eye Galaxy.” Webb’s Mid-InfraRed Instrument (MIRI) sees that dust, shown in red, as it absorbs and re-emits light from surrounding newborn stars. These young stars are embedded in pink star-forming regions in the secondary Hubble-only image. M64’s inner and outer gas regions counter-rotate, creating regions of increased star formation where the two gas “currents” meet and compress. A merger between M64 and a smaller galaxy was likely the cause of the opposing motion of the outer gas. Spiral galaxies were once thought to have peaceful histories. M64 was key evidence that spiral galaxies, including the Milky Way, can and do experience mergers. Webb’s view of M64 will tell astronomers about the structure, motion, and composition of the galaxy’s dust and add context to the galaxy’s merger history and evolution.

Explanation: This treasure chest is full of stars. The featured image was obtained with NASA's James Webb Space Telescope and shows a dust pillar in the Carina Nebula inside our Galaxy, roughly 7500 light-years away. It is formed by interstellar gas and dust, and shaped by powerful stellar winds and radiation form neighboring stars like the nearby Eta Carinae stellar system which is more luminous than 5 million suns. The star formation inside the pillar is excavating its head, creating the open lid of the chest. Astronomers estimate that there are about 70 stars in a compact cluster inside the pillar. This cluster is now thought to be only around 1.3 million years old. Its bounty of young stars includes a massive star approximately 19 times as massive as the Sun. More massive stars are rarer, shine brighter and evolve faster than less massive stars. They are the shiniest jewels in the treasure chest.

Explanation: The small, northern constellation Triangulum harbors this magnificent face-on spiral galaxy, Messier 33. Its popular names include the Pinwheel Galaxy or just the Triangulum Galaxy. M33 is over 50,000 light-years in diameter, third largest in the Local Group of galaxies after the Andromeda Galaxy (M31), and our own Milky Way. About 3 million light-years from the Milky Way, M33 is itself thought to be a satellite of the Andromeda Galaxy and astronomers in these two galaxies would likely have spectacular views of each other's grand spiral star systems. As for the view from the Milky Way, this sharp telescopic image shows off M33's blue star clusters and pinkish star forming regions along the galaxy's loosely wound spiral arms. In fact, the cavernous NGC 604 is the brightest star forming region, seen here at about the 5 o'clock position from the galaxy center. Like M31, M33's population of well-measured variable stars have helped make this nearby spiral a cosmic yardstick for establishing the distance scale of the Universe.

Explanation: Also known as the false dawn, a luminous band of zodiacal light is captured in this dark night skyscape. The serene view was recorded just before the beginning of astronomical twilight during September's star party at the remote Hanle Dark Sky Reserve, Ladakh, India, planet Earth. At about 4,500 meters altitude, the dark sky reserve presents a haven for hardy stargazing and astrophotography enthusiasts. While meteors streak through the night, bright planet Jupiter appears immersed in the faint zodiacal glow near the eastern horizon. Follow the zodiacal band toward the zenith to find open star cluster M44 and a yellowish tinged planet Mars near the center of the frame. In fact, serendipitous detections of interplanetary dust by NASA's Juno spacecraft suggest Mars itself is the source of dust that back scatters sunlight and creates zodiacal light in planet Earth's night.

Explanation: If you went outside at the same time every day and took a picture that included the Sun, how would the Sun's position change? A visual answer to that question is an analemma, a composite image taken from the same spot at the same time over the course of a year. The featured analemma was composed from images taken every few days at noon near the village of Callanish in the Outer Hebrides in Scotland, UK. In the foreground are the Callanish Stones, a stone circle built around 2700 BC during humanity's Bronze Age. It is not known if the placement of the Callanish Stones has or had astronomical significance. The ultimate causes for the figure-8 shape of this and all analemmas are the tilt of the Earth axis and the ellipticity of the Earth's orbit around the Sun. At the solstices, the Sun will appear at the top or bottom of an analemma. The featured image was taken near the December solstice and so the Sun appears near the bottom. Equinoxes, however, correspond to analemma middle points -- not the intersection point. In two days there will be an equinox ("equal night"), when day and night are equal over all of planet Earth. Many cultures celebrate a change of season at an equinox.

Explanation: When does a nebula look like a comet? In this crowded starfield covering over two degrees within the high-flying constellation of the Swan (Cygnus), the eye is drawn to the Cocoon Nebula. A compact star forming region, the cosmic Cocoon punctuates a nebula bright in emission and reflection on the lower right, with a long trail of interstellar dust clouds to the left, making the entire complex appear a bit like a comet. Cataloged as IC 5146, the central bright head of the nebula spans about 10 light years, while the dark dusty tail spans nearly 100 light years. Both are located about 2,500 light years away. A bright star near the colorful nebula's center likely supplies power and helps clear out a cavity. The long dusty filaments of the tail, although dark in this visible light image, hide stars in the process of formation. The featured image was captured in July from Death Valley, California, USA.

Explanation: This shot captured an unexpected silhouette. Which is it? It isn't the sunspots, the small dark regions caused by concentrated magnetic fields visible around the Sun's bright disk. Sunspots typically last for weeks and were expected, since these spots were seen previously. It isn’t the International Space Station (ISS), the small dark structure on the middle left.  This is because the featured picture was planned with sub-second timing to record the iconic structure passing before the Sun. It is the airplane. Just as this exposure was taking place in June, from Prasek in the Czech Republic, an airplane began its own miniature partial eclipse. The result is this triply aligned image of our Sun. The photographer estimates that the chance of any random Sun image containing silhouettes of both a space station and an airplane, from that location, is about 30 million to one. 

Explanation: A once-in-a-lifetime crater has appeared on the Moon! A comet or asteroid roughly the size of a humpback whale (approximately 10-20 meters, 30-60 feet) crashed into the Moon sometime between April and May of 2024. The Lunar Reconnaissance Orbiter (LRO), with its monthly monitoring of the Moon, captured today’s images of the lunar surface before and after the event. The resulting crater, named after Apollo-era lunar scientist McGetchin, is two soccer fields across. Craters of this size are only expected once every 132 years! Follow up thermal imaging revealed a large cold spot that surrounds the warm crater. Surface impacts will puff up the loose lunar sediment, or regolith, making it less dense and harder to retain heat. This event affected an area much larger than the visible crater, which will inform humanity’s understanding of surface impacts and the evolution of the Moon’s surface. It also reminds us all to be thankful for Earth's atmosphere.

Explanation: The ghosts of five supernovas haunt this extraordinary image. It was acquired at Oukaïmeden Observatory in Morocco with approximately 200 hours of observations and shows a large patch of the sky, equivalent to the area of one thousand full moons tiled together, in the constellation of Auriga (the Charioteer). From left to right, the five supernova remnants visible across the field are G181.1+9.5, G182.4+4.3, G179.0+2.6, G180.0−1.7 (Sh2-240, the Spaghetti Nebula), and G178.2−4.2. They are highlighted in the annotated image, together with open cluster M37 and the Tadpole Nebula. As each explosion expanded into space, it created a growing shell of shocked gas and delicate filamentary structures shown in red (hydrogen) and blue (oxygen), respectively. These ancient stellar explosions happened independently; they are at various distances up to about several thousands of light-years away from Earth and have estimated ages up to tens of thousands of years old. Early humans may have witnessed them as bright new stars, fading over weeks or months.

Explanation: On August 15, this perseid meteor streaked through night skies over the Observatorio del Roque de los Muchachos at La Palma, Canary Islands, Spain. The bright and colorful meteor trail was captured next to the central Milky Way, whose dark interstellar dust clouds and luminous starlight reach above the horizon. In the foreground of this tantalizing celestial scene is the 23 meter diameter mirror of the prototype Large-Sized Telescope (LST-1). LST-1 is the first telescope constructed at the northern hemisphere site of the innovative Cherenkov Telescope Array Observatory. With 198 hexagonal mirror segments and a large, high-efficiency, pixelized camera, LST-1 is designed to detect extremely brief, atmospheric visible light flashes. Lasting about a billionth of a second, the visible light flashes are triggered by energetic gamma-rays from cosmic sources such as distant active galaxies and gamma-ray bursts. Of course, on that night some individual mirror segments of LST-1 also reflected the atmospheric flash of the bright perseid meteor.