APOD

Astronomy Picture of the Day

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.

APOD’s main NASA site is moving: From apod.nasa.gov to science.nasa.gov/apod
Tomorrow’s picture: star party weekend

Date	September 18, 2026
Credit & Copyright:	George Chatzifrantzis
Authors & editors:	Jerry Bonnell, Cecilia Chirenti, Robert Nemiroff, Keighley Rockcliffe
A service of:	ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U.

Source: science.nasa.gov

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.

Text credit: ESA/Hubble

Media Contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
[email protected]

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UC Berkeley engineers and managers watch as the COSI (Compton Spectrometer and Imager) detector assembly is slowly raised from a table in this July 8, 2026, image. The four pieces of silver material on the top of the detector box cover the flex circuits, which carry signals from the detectors to the readout electronics.

COSI is a wide-field gamma-ray telescope that will study energetic phenomena in the Milky Way and beyond, including the creation and destruction of matter and antimatter and the final stages of the lives of stars. The mission is a collaboration between the University of California, Berkeley’s Space Sciences Laboratory; the University of California, San Diego; the Naval Research Laboratory; NASA’s Goddard Space Flight Center; Northrop Grumman; Space Dynamics Laboratory; the Italian Space Agency; and a number of research institutions.

Image credit: UC Berkeley/Alan Toth

Source: www.nasa.gov

To continue regular crew transportation to the International Space Station, NASA has awarded SpaceX three additional missions through a contract modification.

As part of the agency’s Commercial Crew Transportation Capability (CCtCap) contract, this change brings the total missions for SpaceX to 17 and helps NASA to maintain access to the space station with two unique commercial crew industry partners.

This is a firm fixed-price, indefinite-delivery/indefinite-quantity contract modification for the Crew-15, Crew-16, and Crew-17. The value of this modification for all three missions and related mission services is $946 million. The amount includes ground, launch, in-orbit, and return and recovery operations, cargo transportation for each mission, and a lifeboat capability while docked to the International Space Station. The period of performance runs through 2030 and brings the total CCtCap contract value with SpaceX to $5.92 billion.

The award follows the agency issuing a notice of intent in May to purchase the additional missions. The current sole source modification does not preclude NASA from seeking future contract modifications for additional transportation services, as needed.

In 2014, NASA awarded the CCtCap contracts to Boeing and SpaceX through a public-private partnership as part of the agency’s Commercial Crew Program. Under CCtCap, NASA certifies that a provider’s space transportation system meets the agency’s requirements prior to flying missions with astronauts.

SpaceX was certified by NASA for crew transportation in November 2020. The company’s twelfth crew rotation mission for the agency, the Crew-12 mission, is currently in orbit docked to the space station. As part of the missions, SpaceX’s Dragon spacecraft and Falcon 9 rocket transport up to four astronauts, along with critical cargo, to the space station.

For information about NASA’s Commercial Crew Office, visit:

https://www.nasa.gov/exploration/commercial/crew

Source: www.nasa.gov

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.

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. 

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.”

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.  

To learn more about the XRISM mission, visit:

https://nasa.gov/xrism

Source: science.nasa.gov

Long before they helped shape NASA’s future aerospace breakthroughs, Derek Abramson, Justin Hall, and Justin Link were in their garages and homes building radio‑controlled aircraft, testing new ideas, and flying their creations at hobby events. That early passion now fuels the work of NASA’s Dale Reed Subscale Flight Research Laboratory at the agency’s Armstrong Flight Research Center in Edwards, California.

At NASA Armstrong’s subscale flight lab, the team turns that lifelong enthusiasm into mission-focused innovation. The laboratory supports research that ranges from advanced navigation systems for future landings on the Moon and Mars to emerging aeronautics concepts that need quick, low-cost evaluation. NASA’s small, remotely piloted and autonomous aircraft allow engineers to explore ideas that could be difficult, risky or expensive to test at full scale.

Skilled team

Abramson, Hall, and Link play key roles in that work. Abramson serves as the laboratory’s chief engineer. Hall is the chief pilot. Link is a drone pilot. Together, they integrate emerging aerospace technologies with the lab’s subscale aircraft fleet and, when needed, design and build aircraft or flight experiments to evaluate new concepts.

Abramson’s expertise, built through service in the U.S. Navy and the aerospace industry, centers on technical oversight, management, and system design. Hall is known for creative approaches to problem solving and uses practical methods to address technical challenges and maintain flight safety. Link specializes in designing and fabricating research vehicles and draws on extensive hands-on experience to understand what works, and what does not, in flight. 

On weekends, the team often tinkers in their garages or hangars building radio-control aircraft, researching hobby trends, or exploring new technologies. You might see them flying their creations at hobby events or attending trade shows. Their passion for flight brought Abramson, Hall, and Link together years before they one-by-one joined NASA more than a decade ago, though each discovered that spark in a different way.

Early influences

Abramson’s interest began as a child with rubber-band powered stick and tissue aircraft and radio-controlled models. His early aviation pursuits led to his first solo flight while in high school and a pilot’s license. In the Navy, he worked on multiple aircraft, including EA-6B and the F-18, as an avionics technician. As an engineer, he supported the B-1 and CV-22 Osprey aircraft flight tests. As an intern at NASA Armstrong, he used his operational and engineering experience on remotely piloted and autonomous aircraft.

Hall’s interest grew after seeing historic aircraft including the Mach 3 SR-71 fly over his elementary school playground and watching Space Shuttle Challenger land from above his dad’s shoulders. He has built and flown model and remotely piloted aircraft for as long as he can remember. His reputation flying radio-controlled hobby aircraft at fly-ins and trade events led to an offer to fly subscale aircraft at NASA.

Link was five years old when he built balsa-wood aircraft with his dad and flew them in a field near their home. As he grew older, his hobby expanded to include radio-controlled cars, boats, helicopters, and aircraft. Aviation runs deep in Link’s family. His great grandfather served in the U.S. Army Air Corps, his grandfathers served in the U.S. Air Force, and his dad was an Air Force avionics technician. Link raced sailplanes, competed with scaled warbird aircraft, and was encouraged by family and friends to pursue an aviation profession. He has worked with large drones for more than 11 years, focusing on research and development, composite materials, and specialized fabrication methods.

Together, the team applies its experience and knowledge in rapid design, fabrication, integration and flight testing to bring new ideas to flight. Their work continues to support NASA’s missions across aeronautics, science, and exploration.

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APOD

Astronomy Picture of the Day

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 Treasure Chest in the Carina Nebula

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 from 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.

APOD’s main NASA site is moving : From apod.nasa.gov to science.nasa.gov/apod
Tomorrow’s picture: The Triangulum Galaxy

Date	September 17, 2026
Credit	ESA/Webb, NASA & CSA, M. Reiter; Acknowledgement: M. H. Özsaraç
Authors & editors:	Cecilia Chirenti, Robert Nemiroff, Jerry Bonnell, Keighley Rockcliffe
A service of:	ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U.

Source: science.nasa.gov

Fifty years ago, on Sept. 17, 1976—Constitution Day of America’s bicentennial year—NASA unveiled its first space shuttle orbiter, OV-101, to the public. NASA had originally planned to name the vehicle Constitution, but a letter-writing campaign changed the agency’s plans. Nearly 100,000 fans of the Star Trek television series wrote the White House urging that the shuttle be named after the USS Enterprise, the fictional starship featured in the series. In a memo, President Gerald Ford directed NASA to christen the shuttle Enterprise saying he was “partial to the name”. The name Enterprise, long celebrated in U.S. naval history, had earlier been bestowed on the first nuclear-powered carrier, a World War II carrier, and an American vessel of the Revolutionary War.

Hundreds of invited guests attended the rollout ceremony at Rockwell’s Palmdale facility in southern California, including Star Trek creator Gene Roddenberry and several cast members. Pictured from left to right in this photo are NASA Administrator James C. Fletcher, DeForest Kelley (Dr. “Bones” McCoy), George Takei (Mr. Sulu), James Doohan (Chief Engineer Montgomery “Scotty” Scott), Nichelle Nichols (Lt. Uhura), Leonard Nimoy (Mr. Spock), series creator Gene Rodenberry, U.S. Rep. Don Fuqua (D.-Fla) and Walter Koenig (Ensign Chekov).

Even though Enterprise was not designed to fly in space, it performed the essential atmospheric test flights that paved the way for the shuttle program’s first spaceflights in 1981. The orbiter is now on display at the Intrepid Museum in New York City.

Learn more about the historic rollout of NASA’s first space shuttle.

Credit: NASA

Source: www.nasa.gov

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:

https://media.ksc.nasa.gov

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: [email protected]. 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:

https://www.nasa.gov/station

-end-

Josh Finch / Jimi Russell
Headquarters, Washington
202-358-1100
[email protected] / [email protected]

Steven Siceloff
Kennedy Space Center, Fla.
321-876-2468
[email protected]

Sandra Jones / Joseph Zakrzewski
Johnson Space Center, Houston
281-483-5111
[email protected] / [email protected]

Source: www.nasa.gov

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.

NASA Earth Observatory image by Michala Garrison, using GEOS-FP data from the Global Modeling and Assimilation Office at NASA GSFC. Story by Lindsey Doermann.

Downloads

September 15, 2026

JPEG (1.22 MB)

References & Resources

• AccuWeather (2026, September 11) Latest heat dome to linger in south-central, southeastern US in mid-September. Accessed September 16, 2026.
• Heat.gov (2026) Science and Information to Reduce Heat Risk. Accessed September 16, 2026.
• NOAA National Centers for Environmental Information (2026, September 9) Warmest summer on record for the contiguous U.S. Accessed September 16, 2026.
• The Washington Post (2026, September 15) It’s almost fall, but this record heat dome didn’t get the memo. Accessed September 16, 2026.

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