Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Analemma over the Callanish Stones
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 CallanishStones, 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.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
A Zodiacal Night
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.
The Republic of Albania will sign the Artemis Accords during a ceremony at 12 p.m. EDT on Monday, Sept. 21, at NASA Headquarters in Washington, becoming the 73rd country signatory.
NASA Deputy Administrator Matt Anderson will host Albania’s Minister for Europe and Foreign Affairs Ferit Hoxha and Ambassador of the Republic of Albania to the United States Ervin Bushati for the ceremony, together with U.S. Department of State officials.
In 2020, during the first Trump Administration, the United States, led by NASA and the State Department, joined with seven other founding nations to establish the Artemis Accords, responding to the growing interest in lunar activities by both governments and private companies.
The Artemis Accords introduced the first set of practical principles aimed at enhancing the safety, transparency, and coordination of civil space exploration on the Moon, Mars, and beyond.
NASA-JAXA XRISM Mission Sees Pulsar Gathering Companion’s ‘Wind’
Using data from the Japan-led XRISM (X-ray Imaging and Spectroscopy Mission) observatory, astronomers have directly observed a giant star’s outflow, called a stellar wind, being captured by its compact companion and providing the power source for strong X-ray flares. The research is part of NASA’s exploration of the extreme universe to better understand how the cosmos works.
“We’ve never before seen clear indications of wind plasma falling onto a compact object,” said Roi Rahin, a researcher at UMBC (University of Maryland, Baltimore County) and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We can now test our understanding of these processes in much greater detail.”
A paper describing the findings published Friday in the journal Science Advances.
The target system is BP Crucis, a high-mass X-ray binary located about 13,000 light-years away in the southern constellation Crux. The primary star, known as Wray 977, is a blue hypergiant about 40 times the Sun’s mass and 60 times its size. It’s so big, hot, and luminous that ionized gas constantly streams away from it, a phenomenon astronomers call a stellar wind.
This artist’s concept of the BP Crucis system follows the pulsar on a passage through the dense stream of plasma flowing from its companion, a blue hypergiant 40 times the Sun’s mass. During each four-day passage, the pulsar’s X-ray brightness flares as it pulls in some of the gas. At first, the gas forms a messy, turbulent accretion disk around the pulsar, and plasma spirals down to it. But as the pulsar moves deeper into the stream, there’s not enough angular momentum to support the disk, and it breaks up. At this point, plasma falls straight onto the pulsar. Later, as the pulsar near the end of its passage, a messy accretion disk rebuilds, this time spinning in the opposite direction of the earlier disk due to the stream’s flow. NASA’s Goddard Space Flight Center/Conceptual Image Laboratory
The supergiant’s companion is a tiny-but-mighty neutron star called GX 301-2. The crushed core of a star that long ago exploded as a supernova, it packs more than the Sun’s mass into a ball roughly 12 miles (20 kilometers) across. Rotating every 11 minutes, it sweeps an X-ray beam toward Earth, which classifies it as a pulsar.
Twice during the pulsar’s 41.5-day orbit, near its closest and farthest points from the primary star, strong X-ray flares occur for several days. Astronomers think the pulsar’s gravitational influence on the star creates an especially dense stream of plasma. Flares occur when the pulsar traverses this stream and captures some of its matter. The strongest eruptions happen closer to the star, where the stream is denser.
The researchers targeted the system with XRISM on Feb. 1, 2025, observing it for about 16 hours near the end of one of these stronger flares. The observatory’s Resolve instrument, jointly developed by NASA and JAXA (Japan Aerospace Exploration Agency), captured highly detailed X-ray spectra, revealing rapidly changing emission and absorption lines. In particular, absorption lines from highly ionized iron revealed the speed and direction of plasma relatively close to the pulsar.
Watch to learn about spectroscopy, the dance between matter and light, and how NASA missions using it help scientists answer big questions about our universe. NASA’s Goddard Space Flight Center
When Rahin first saw these spectra, he realized he hadn’t seen anything like them before. He scoured the scientific literature for similar observations and came up empty-handed.
“It was clear that these observations were groundbreaking, but at the same time this meant the analysis had to be especially detailed,” said Nazma Islam, a co-author formerly at UMBC and NASA Goddard and now an assistant professor at Manipal Centre for Natural Sciences, India. “We could see how the dense stream of plasma acts very close to the neutron star.”
The Resolve instrument aboard the NASA-JAXA XRISM observatory captured this high-resolution X-ray spectrum of BP Crucis. Prominent iron absorption lines (dashed) have shifted to lower energies (red lines), which indicates both the direction and velocity of the gas. The observations indicate the gas is moving toward the pulsar at about 335,000 mph (540,000 kph). Data and error bars are shown in gray, with a model spectrum in light blue. Roman numerals indicate the ionization state of iron atoms (the number of electrons they’ve lost to produce each spectral line).
NASA’s Goddard Space Flight Center, JAXA/NASA, Rahin et al. 2026
Rahin and his team show that the iron absorption lines they observed are displaced to lower energies than they would be if measured in a laboratory. This displacement, called a redshift, indicates motion away from the observer, which means the gas is flowing toward the pulsar. The extent of the redshift indicates the plasma’s velocity. The team’s analysis indicates gas is racing toward the pulsar at speeds of around 335,000 mph (540,000 kph).
Here’s what the researchers think is going on: As the pulsar enters the stream, it sweeps up gas into a thick, messy, turbulent disk. This gas spirals down to the pulsar, heats up, and emits X-rays to power the flares.
As the pulsar pushes farther into the stream, the turbulent disk breaks down. Astronomers suspect that as the pulsar moves more directly into the flow, the stream no longer has the angular momentum required to maintain the disk. Once the disk dissipates, plasma flows directly onto the neutron star. Observations with XRISM occurred near the end of this phase.
Then, as the pulsar nears the end of the stream, a messy disk briefly returns, this time spinning in the opposite direction. And then it, too, disappears as the pulsar exits. In all, the pulsar takes about four days to transit the stream.
“The BP Crucis system is an ideal laboratory for studying wind-fed pulsar accretion, and XRISM’s sensitive, high-resolution Resolve spectrometer is an ideal instrument for advancing our understanding of the processes involved,” said Brian Williams, the mission’s project scientist at NASA Goddard.
The spiral galaxy NGC 4698 shines in this image from the NASA/ESA Hubble Space Telescope.
ESA/Hubble & NASA, D. Thilker, the MAUVE-HST Team
Though the spiral galaxy in this new image from the NASA/ESA Hubble Space Telescope seems serene, it hides a chaotic secret. This galaxy is NGC 4698, and it lies about 55 million light-years away in the constellation Virgo. It’s one of over a thousand galaxies in the Virgo Cluster, the nearest large cluster of galaxies bound together by gravity.
As a spiral galaxy similar to our own Milky Way galaxy, NGC 4698 has spiral arms that curl around within a thin disk of stars, gas, and dust. These arms are marked by opaque clumps of brown dust and dotted with small collections of bright blue stars. Unlike many other spiral galaxies, like this one recently photographed by Hubble, NGC 4698’s delicate spiral arms are only prominent in the outer reaches of the disk; spiral arms often wind down to the very center of a galaxy, but NGC 4698’s spiral arms appear to shy away from its glowing center. The arms instead hover in a ring-like structure around the perimeter of the galaxy.
NGC 4698’s center is dominated by an elongated galactic bulge . The diffuse off-white glow of the galaxy’s bulge comes from stars smaller, older, and cooler than the massive blue stars that dot the galaxy’s outer disk. These tightly packed stars orbit a supermassive black hole containing millions of times the Sun’s mass. Scientists have found signs that this black hole is actively growing, drawing gas inward with its gravitational pull.
With a flat, starry disk and diffusely glowing center, NGC 4698 looks a lot like a typical spiral galaxy — but this galaxy is far from normal. NGC 4698 is one of only a few known spiral galaxies with a bulge that extends out from the disk at a right angle. The elongation is faintly visible in this Hubble image, which shows the ghostly glow of the starry bulge peeking above and below the dusty disk. What’s more, the stars and gas nearest the galaxy’s center rotate perpendicular to the rest of the disk!
What could cause a galaxy to be so out of sync? Astronomers have found that the culprit likely lies outside the galaxy. If NGC 4698 funneled in gas from an outside source, the newly collected gas could have formed a disk of gas and stars in the galaxy’s center, at an angle relative to the rest of the disk. Some observations suggest that this galaxy once experienced a minor galactic merger, as evidenced by a short ‘tail’ of hydrogen streaming from one side of the galaxy.
The data used to create this image come from an observing program focusing on galaxies in the Virgo Cluster. This program zooms in on the details of these relatively nearby galaxies, such as individual star clusters and nebulae. At the same time, researchers will use these data to take stock of the larger picture, learning how a galaxy’s journey through a cluster affects the galaxy’s evolution and ability to form new stars.
Our galaxy, the Milky Way, sits in a Local Group of more than 20 galaxies, but Hubble’s vision takes us far beyond our celestial neighborhood. Discover how Hubble’s studies have transformed our understanding of galaxies near and far.
Hubble Focus: Galaxies through Space and Time
Explore the history of galaxies through Hubble’s gaze in this free, downloadable e-book. Spectacular Hubble images and videos bring home the discoveries that have expanded our understanding of galaxies, how they formed, and what they contain.
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Messier 33: The Triangulum Galaxy
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.
NASA has selected SpaceX to provide launch services for the agency’s StarBurst mission, a small satellite designed to investigate neutron star mergers and the origins of short gamma-ray bursts.
StarBurst will launch aboard a Bandwagon rideshare mission on a Falcon 9 rocket from Space Launch Complex 40 at Cape Canaveral Space Force Station in Florida no earlier than 2028.
The selection is a firm-fixed-price task order under NASA’s VADR (Venture-Class Acquisition of Dedicated and Rideshare) launch services contract. This indefinite-delivery/indefinite-quantity contract allows NASA to acquire launch services during a 10-year ordering period, with a maximum total value of $1 billion across all contracts.
The StarBurst mission is designed to observe the entire portion of the sky not blocked by Earth to search for brief, powerful explosions called gamma-ray bursts. The satellite will focus on detecting the initial high-energy emission from short gamma-ray bursts, which occur when dense stellar remnants called neutron stars merge.
By combining StarBurst’s observations with gravitational-wave measurements and follow-up observations from other telescopes, researchers will study these events through multiple types of signals, an approach known as multimessenger astronomy.
StarBurst is part of NASA’s Astrophysics Pioneers Program, which supports lower-cost investigations using small spacecraft and other platforms.
NASA’s Launch Services Program Office, based at the agency’s Kennedy Space Center in Florida, manages the VADR contract.
For more information about NASA’s StarBurst, visit:
A SpaceX Falcon 9 rocket launches on May 15, 2026, carrying about 6,500 pounds of science, supplies, and equipment to the International Space Station during the company’s 34th commercial resupply mission for NASA.
Credit: NASA
Media accreditation is open for the next cargo launch that will deliver NASA science investigations, supplies, and equipment to the International Space Station. The 35th SpaceX commercial resupply services mission to the orbital laboratory for NASA will lift off on a Falcon 9 rocket.
NASA and SpaceX are targeting no earlier than October to launch the SpaceX Dragon spacecraft from Cape Canaveral Space Force Station in Florida.
Credentialing to cover prelaunch and launch activities is open to U.S. media only. The application deadline is 11:59 p.m. EDT, Thursday, Oct. 1. All accreditation requests must be submitted online at:
Media will receive a confirmation email upon approval. NASA’s media accreditation policy is available online. For questions about accreditation, or to request special logistical support, email: ksc-media-accreditat@mail.nasa.gov. For other questions, please contact NASA’s Kennedy Space Center newsroom at: 321-867-2468.
Each resupply mission to the station delivers scientific investigations in biology and biotechnology, Earth and space science, physical sciences, and technology development and demonstrations. Cargo resupply from U.S. companies ensures a national capability to deliver scientific research to the space station, significantly increasing NASA’s ability to conduct new investigations aboard humanity’s laboratory in space.
In addition to food, supplies, and equipment for the crew, Dragon will deliver the final sets of International Space Station Roll-Out Solar Arrays, called IROSA, which astronauts will install during future spacewalks to complete station’s power augmentation. Once installed, the arrays will provide additional power to support critical station operations, including its safe and controlled deorbit.
The mission also will transport several new experiments to the orbital complex, including hardware to manufacture artificial retinas in microgravity that could help restore vision for patients on Earth and 3D heart cell models to advance large-scale drug testing on future space missions. Dragon also will carry materials to study how a new type of glass is formed in microgravity, and brain organoids that could uncover potential treatment targets for neurodegenerative diseases like Alzheimer’s, Parkinson’s, and multiple sclerosis.
For more than 25 years, people have lived and worked continuously aboard the International Space Station, advancing scientific knowledge and making research breakthroughs not possible on Earth. The space station helps NASA understand and overcome the challenges of human spaceflight, expand commercial opportunities in low Earth orbit, and build on the foundation for long-duration missions to the Moon, as part of the Artemis program, and to Mars.
Learn more about NASA’s commercial resupply missions at:
An area of high pressure over the south-central U.S. produced unseasonable and, in some places, record-breaking warmth on September 15, 2026, as shown in this map of modeled air temperatures from GEOS (Goddard Earth Observing System).
NASA Earth Observatory/Michala Garrison
While the calendar indicated that astronomical summer was winding down, a swath of the south-central United States was sweltering under a heat dome in mid-September 2026.
This map shows air temperatures in the contiguous U.S. on September 15, 2026, at 4 p.m. Central Time (21:00 Universal Time), modeled at 2 meters (6.5 feet) above the ground. It was produced by combining satellite observations with temperatures predicted by a version of the GEOS (Goddard Earth Observing System) model, which uses mathematical equations to represent physical processes in the atmosphere. The darkest reds indicate areas where temperatures approached or exceeded 40 degrees Celsius (104 degrees Fahrenheit).
More than 41 million people in the U.S.—about 12 percent of the population—were under a National Weather Service extreme heat advisory, extreme heat watch, or extreme heat warning on September 15. The high temperatures spanned large portions of several states, such as Texas, Oklahoma, Arkansas, Missouri, and Tennessee. Meteorologists warned that high humidity, limited cloud cover, and light winds could make temperatures feel higher than thermometer readings and increase the risk of heat-related illnesses.
Several locations set new daily high temperature records on September 15. These included Dallas, Texas, at 101ºF (38ºC), Memphis, Tennessee, at 99ºF (37ºC), and Nashville, Tennessee, at 100ºF (38ºC). The cities were all at least 12ºF warmer than normal that day, with Nashville breaking its daily-high record from 1927. The day before, Nashville also set a record-high minimum temperature of 75ºF (24ºC).
A weather phenomenon meteorologists call a heat dome was responsible for driving temperatures up across the region. A heat dome develops when an area of high pressure in the upper atmosphere pushes hot air toward the surface and traps it there. Heat domes put the brakes on convection and suppress clouds and precipitation. This allows sunlight to reach Earth’s surface relatively unhindered and further elevate air temperatures.
The stretch of unseasonable temperatures follows the warmest June through August in the contiguous United States in a 132-year record, according to NOAA. The three-month period in 2026 was 0.4ºF warmer than the previous records, set in 1936 and 2021.
