Image of the Week

31 July 2024: NSF–DOE Vera C. Rubin Observatory atop Cerro Pachón in Chile is outlined against the full Moon rising above the horizon. A trick of perspective has enlarged the Moon beyond the size we’d naturally see it on Earth in this Image of the Week. Often regarded as an ‘enemy’ of non-lunar astronomers because of its brightness, the beauty of Earth’s natural satellite cannot be ignored. On the right side of the Moon in this image is the large and relatively young Tycho crater, with its distinctive ray system prominently spreading across the lunar surface. On the bottom and left side are large, dark maria, basaltic plains that formed during the early life of the Moon 1.2–4 billion years ago. The largest of the maria in this image is the Sea of Tranquility, the first site on the Moon visited by humans. This image was captured during the final phase of the …

24 July 2024: This ghostly, butterfly-shaped planetary nebula, captured with Gemini North, one half of the International Gemini Observatory, supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab, is known as Kohoutek 3-46. Kohoutek 3-46 derives its name from the prolific planetary nebula hunter who discovered it, Czech astronomer Luboš Kohoutek. Located in the constellation Cygnus, Kohoutek 3-46 is estimated to be around 20,000 years old and around 7200 light-years away. The term ‘planetary nebula’ is a misnomer, since these nebulae are unrelated to planets. The term originates from their planet-like round shape, more obviously seen in this earlier NOIRLab Image of the Week. Kohoutek 3-46 has expanded into an unusual bipolar shape, classified by its well-defined hourglass shape, prominent equatorial ring and marked waist. About 10–20% of planetary nebulae are bipolar. No matter the shape they take on, these glowing clouds of gas form after a star …

17 July 2024: Stars swirl around the south celestial pole in this timelapse image of the night sky captured at the Víctor M. Blanco 4-meter Telescope. The Blanco Telescope is located on the summit of Cerro Tololo in northern Chile, home to the U.S. National Science Foundation Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF NOIRLab. Photographers create timelapses like this by combining multiple long-exposure images of the night sky. As Earth rotates throughout the night, the stars appear to circle the north or south celestial poles. The southern hemisphere’s pole star, Sigma Octantis, is located in the middle of the ‘vortex’ in the image. It is fainter than the northern hemisphere’s more recognizable pole star, Polaris. To the upper left of the Blanco telescope, the illuminated pathways of two satellites intersect the star trails. The red squiggles in the foreground were created by someone walking with a red flashlight. Red lights …

10 July 2024: Majestic as it is mysterious, the Milky Way can easily illuminate the night sky in a dazzling flourish with just the right camera setting. Containing an estimated 100–400 billion stars, our barred spiral galaxy, the Milky Way, intertwines with interstellar dust to create a brilliantly complex bridge of light sprinkled across the sky. At the end of this bridge on the left lies Gemini North, the northern twin of the International Gemini Observatory, supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab. Standing near the summit of Maunakea in Hawai‘i, the telescope’s location places it far away from light pollution and right among the stars for proper astronomical study. At the center, below the cloud deck forming at the bottom of the image, are the trapped city lights of Hilo. On the right, the faint glow of lava from the Kīlauea volcano lights up a …

3 July 2024: Home to over twenty optical and two radio telescopes, the U.S. National Science Foundation Kitt Peak National Observatory (KPNO), a Program of NSF NOIRLab, is located at the highest point on the Quinlan Mountain in the Arizona-Sonoran Desert on the Tohono O’odham Nation, southwest of Tucson, Arizona. On the right is the Nicholas U. Mayall 4-meter Telescope, which was the world’s second-largest telescope when it was built in 1973. On the left is the UArizona Bok 2.3-meter Telescope, operated by Steward Observatory at the University of Arizona. KPNO’s distance from heavily light-polluted areas — like the cities and towns on the horizon — makes it an ideal place for observing faint astronomical objects. In this picture, the photographer has captured two phenomena that are difficult to observe in areas affected by heavy light pollution. First is the faint arcing glow in the sky known as zodiacal light. This light glow …

26 June 2024: The Great Rift appears to split the Milky Way above NSF–DOE Vera C. Rubin Observatory, a Program of NSF NOIRLab, on Cerro Pachón in this Image of the Week. This prominent dark region is a series of cold dust clouds full of active star formation. However, these clouds are so dense that they block light from the stars behind them and create the ‘rift’. Rubin Observatory, jointly funded by the U.S. National Science Foundation (NSF) and the U.S. Department of Energy (DOE), will begin science operations in late 2025. When complete, Rubin Observatory will use its 8.4-meter mirror and the largest camera ever built for astronomy to begin an ambitious decade-long survey known as the Legacy Survey of Space and Time (LSST). Every 3–4 nights the telescope will image the entire southern sky to build a wealth of data with which to answer some of the most challenging questions about …

19 June 2024: This unbarred spiral galaxy in the constellation Crater features a bright central core, where a supermassive black hole lies, surrounded by a disk of hot, young stars and spiral arms laced with streams of dust and more young stars. The irregular, outstretched shape of its arms is likely due to gravitational influence from an encounter with one of its galactic neighbors. NGC 3981 is a member of the NGC 4038 Group of galaxies, which also contains the well-known interacting Antennae Galaxies. The NGC 4038 Group is a small component of the Virgo Supercluster, the immense collection of galaxies that hosts our own Milky Way Galaxy. The unfurling arms of NGC 3981 appear to dissolve right into the cosmos in this image captured by the DOE-built Dark Energy Camera (DECam) on the Víctor M. Blanco 4-meter Telescope at the U.S. National Science Foundation Cerro Tololo Inter-American Observatory (CTIO), a Program of …

12 June 2024: The Geminids meteor shower puts on its annual cosmic performance, filling the night sky with streaks of light above the U.S. National Science Foundation Kitt Peak National Observatory, a Program of NSF NOIRLab, outside of Tucson, Arizona. Meteor showers happen when Earth passes through debris left by a comet or asteroid; this debris enters our atmosphere and ignites into fiery streaks in the sky called meteors. Any bits of material that land on Earth’s surface without burning up in the atmosphere are called meteorites. Not only do the clear skies common in Arizona make it a great place to observe meteor showers, but the desert environment preserves meteorites on the ground. In more humid regions meteorites weather away more quickly; Arizona’s dry air and infrequent rain showers allow them to remain intact and discoverable for longer periods. Because of the ease of finding meteorites, Arizona boasts a large community of …

5 June 2024: Gemini North, the northern half of the International Gemini Observatory, supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab, sits at over 4000 meters (nearly 14,000 feet) above sea level, perched near the summit of Maunakea, in Hawai‘i. Prominent in this image are the photovoltaic (PV) solar panels that were installed on the roof of the telescope building in 2015. These panels generate about twelve percent of the power required to run Gemini North, supplementing grid power for the telescope during daylight hours. At its high elevation above the clouds, the facility gets more power from this ~100 kW PV system than can be produced from a similar system at sea level. Through its Environmental Sustainability Program, NOIRLab will reduce its entire annual carbon footprint by 50% by the end of 2027.

29 May 2024: Vera C. Rubin Observatory sits under the faint glow of a fascinating astronomical phenomenon known as zodiacal light. It appears as a faint, cone-shaped glow that extends along the path followed by the planets and Sun (known as the ecliptic) and is caused by sunlight reflecting off interplanetary dust that sits in the plane of our Solar System. This phenomenon is most easily seen in the western sky just after sunset or in the eastern sky just before sunrise. The dust is thought to be left by comet tails and collisions between asteroids. Zodiacal light is faint and usually drowned out by light-polluted skies or glare from the Moon. The NSF–DOE Vera C. Rubin Observatory is funded by the U.S. National Science Foundation (NSF) and the U.S. Department of Energy’s Office of Science (DOE/SC). Rubin Observatory is a Program of NSF NOIRLab, which, along with DOE’s SLAC National Accelerator Laboratory, …

22 May 2024: Collectively known as RSCG 55, this captivating spectacle of gravitationally intertwined galaxies lies in the constellation Virgo. This image was taken by the Dark Energy Camera (DECam) which was built by the Department of Energy and mounted on the prime focus of Víctor M. Blanco 4-meter Telescope at the U.S. National Science Foundation Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF NOIRLab, in Chile. This is a group of interacting galaxies, meaning they are located close enough to influence each other gravitationally. Over time, gravitational interactions can greatly impact how galaxies evolve, leading to distorted shapes, increased rates of star formation, and galactic mergers. Gravitational interactions between galaxies have had a big impact on the variety of galaxies we see in the Universe today. What evidence of gravitational interaction can you see in this image? The most obvious examples are the well-defined tidal bridges which appear as faint trails …

15 May 2024: The U.S. National Science Foundation Kitt Peak National Observatory (KPNO), a Program of NSF NOIRLab, is home to twenty optical and two radio telescopes, making it one of the largest collections of astronomical instruments in the northern hemisphere. The two telescopes that can easily be seen here are the Nicholas U. Mayall 4-meter Telescope on the left and the UArizona Bok 2.3-meter Telescope on the right. High in the sky to the right over the Mayall Telescope are the familiar stars of the Big Dipper, an asterism of the larger constellation Ursa Major (the Great Bear). This stellar collection is circumpolar, meaning that they are so close to the north celestial pole that they never set below the horizon at most latitudes in the northern hemisphere. They are even in the sky during the day, though they can’t be seen because the direct sunlight is much brighter. The faint glow …

8 May 2024: In this photo the full Moon can be seen rising over Maunakea. The dormant volcano is home to the Gemini North telescope, one half of the International Gemini Observatory, supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab, and also a number of other observatories. The dark form below the Moon is the shadow of Maunakea. Because of an optical effect, the shadow appears triangular, even though Maunakea itself is not. The shadow of the volcano is simply so long that any irregularities blur into a rectangle, which tapers off into the distance before appearing to converge at a single point on the horizon, an effect caused by both the curvature of the Earth and the geometric perspective. While the summit of Maunakea is very dry, the island of Hawai‘i is tropical and often cloudy because of the high humidity. The difference in altitude from …

1 May 2024: This Image of the Week shows the assiduous telescopes of the Southern Astrophysical Research Telescope (SOAR, center), and International Gemini Observatory (right) below the dusty Milky Way and atmospheric airglow. SOAR is one of almost 40 telescopes at the U.S. National Science Foundation Cerro Tololo Inter-American Observatory (CTIO), a Program of NSF NOIRLab. To the bottom-left of SOAR is a photographer looking out onto the arid landscape of Cerro Pachón in Chile, highlighting the large scale of the 4.1-meter telescope. Behind SOAR, the Gemini South telescope, one half of the International Gemini Observatory, operated by NSF NOIRLab, can be seen operating its laser guide star. This is an artificial star created to aid the adaptive optics system to correct for optical distortions in Earth’s atmosphere. Adaptive optics systems must have a pinpoint light source to guide their operation, but only a few stars across the vast sky are bright enough …

24 April 2024: This aerial drone view shows the Southwest Ridge of the U.S. National Science Foundation Kitt Peak National Observatory (KPNO), a Program of NSF NOIRLab, recovering from the Contreras Fire that reached the observatory grounds in June 2022. In the distance are the Hiltner 2.4 meter (left) and McGraw Hill 1.3 meter (right) reflecting telescopes that constitute the MDM Observatory that is owned and operated by a consortium of universities — University of Michigan, Dartmouth, University of Ohio, Ohio State University, and Columbia University. At work in the lower right corner is the UArizona 12-meter Telescope, a radio telescope, inside its dome. Operators of optical telescopes must wait for nightfall to do their observing as light from distant objects is outshone by the Sun during the day. The Sun’s emission at radio frequencies is, however, comparatively weak, and therefore won’t interfere with radio frequencies received by telescopes, enabling round-the-clock observations. Furthermore, …

17 April 2024: Surrounding the Gemini North telescope are three natural light phenomena that can only be seen in the darkest of skies. These dark skies surround this half of the International Gemini Observatory, supported in part by the U.S. National Science Foundation and operated by NSF NOIRLab, isolated in the middle of the Pacific Ocean at an altitude of 4214 meters (13,825 feet). High above the nearby cities on the summit of Hawai‘i’s Maunakea the sky avoids the light pollution from city lights and gives way instead to the natural atmospheric and interplanetary phenomena caused by solar activity. Arching over Gemini North is the faint glow of zodiacal light, along with a patch of brightness called the Gegenschein, both caused by sunlight scattering off a large ring of dust around our Sun. Along the horizon is airglow of atmospheric origin. Airglow forms when molecules in the upper atmosphere become excited by the …

10 April 2024: The very unusual galaxy NGC 2685, also known as the Helix Galaxy, is located about 40 million light-years away in the constellation Ursa Major. This image was captured by the Gemini North telescope, one half of the International Gemini Observatory, operated by NSF NOIRLab which is funded by the U.S. National Science Foundation. NGC 2685 is a peculiar lenticular galaxy known as a polar ring galaxy. A ring of gas, stars, and dust orbits NGC 2685 perpendicular to the flat plane of the host galaxy. This odd crossing of planes is believed to be evidence of galaxy interactions, mergers, or tidal accretion events. Current research suggests that the present structure of NGC 2685 was formed when it captured material from another galaxy, which was strung out into an encircling ring. This galaxy is one of our closest known polar ring galaxies and is therefore one of the easiest of its …

3 April 2024: Two lines of light — one the arm of our Milky Way and the other zodiacal light — rise parallel to each other from the horizon above U.S. National Science Foundation Cerro Tololo Inter-American Observatory (CTIO) in this Image of the Week. CTIO is a Program of NSF NOIRLab situated in the high, dry environment of the remote mountain of Chile, where sensitive equipment can capture the subtleties of light in our night sky. Between the DIMM1 Seeing Monitor and decommissioned CHilean Automatic Supernova sEarch (CHASE) is one arm of our galaxy. Its glow, formed by unresolved stars and other material, is obscured here and there by dark patches, made up of vast amounts of dust and gas. To the right of the Milky Way is the faint glow of zodiacal light, sunlight that is being scattered by interplanetary dust left over from the formation of our Solar System. This …

27 March 2024: As the Sun sets over Maunakea, one of the volcanoes constituting the island of Hawai‘i, a soft golden glow washes over the telescopes that call the mountain home. For many, golden hour signifies the closing of a day, the time to begin preparing for sleep. But for staff at Gemini North (left), one half of the International Gemini Observatory, operated by NSF NOIRLab which is funded by the U.S. National Science Foundation, golden hour signifies the beginning of the work day. As soon as the Sun dips below the horizon, the telescope domes open and the telescope comes to life. Also pictured here is the Canada-France-Hawai‘i Telescope (right) and, in the distance from left to right, the Subaru Telescope, W. M. Keck Observatory, and NASA Infrared Telescope Facility. All the telescopes on Maunakea are part of the Maunakea Observatories. This photo was taken as part of the NOIRLab 2022 Photo …

20 March 2024: A rainbow rises to the clouds over Kitt Peak National Observatory (KPNO), a Program of NSF NOIRLab. This image, taken during one of the public stargazing programs at Kitt Peak, features the KPNO 2.1-meter telescope (right), operated by NOIRLab, and the Robotically Controlled Telescope (left), operated by the RCT consortium. In addition to cameras, many of the telescopes at KPNO are equipped with spectrographs which separate the light into its constituent colors, just as water droplets in rain clouds split sunlight into a rainbow. Knowing the amount of light that a celestial object produces at each wavelength allows scientists to measure the object’s various properties. With spectroscopy, we’ve measured the composition of exoplanetary atmospheres, the metallicity of stars, the motion of celestial planets, and the distances to far-away galaxies. More information can be learned through spectroscopy than from imaging alone, making it a crucial tool for studying the Universe.