NASA astronaut Anil Menon poses in a spacesuit for a portrait at NASA’s Johnson Space Center in Houston, Texas on Jan. 8, 2026. Menon will launch aboard the Roscosmos Soyuz MS-29 spacecraft to the International Space Station on Tuesday, July 14, accompanied by cosmonauts Pyotr Dubrov and Anna Kikina, where they will join the Expedition 74 crew advancing scientific research. During his stay on the station, Menon will conduct scientific research and technology demonstrations aimed at advancing human space exploration and benefiting life on Earth.
NASA’s Hubble Discovers First of Star Cluster’s Missing Black Holes
An image of the globular cluster Omega Centauri, a collection of myriad stars colored red, white, and blue on the black background of space.
Credits: Science: Maximilian Häberle (MPIA)
The massive globular star cluster Omega Centauri has puzzled astronomers for decades. It should be filled with black holes left behind by exploding stars, yet evidence for them is scarce. Now, astronomers using archival data from NASA’s Hubble Space Telescope and supportive observations from NASA’s James Webb Space Telescope have finally located their first stellar-mass black hole in this cluster. Discovering the first of this missing black hole population will help refine current theories on black hole formation within environments such as Omega Centauri. The team’s findings published Monday in The Astrophysical Journal Letters.
Omega Centauri is composed of 10 million gravitationally bound stars. Though the astronomical community previously found evidence with Hubble that an intermediate-mass black hole lurks at its center, models suggest this star cluster should also contain about 10,000 smaller, stellar-mass black holes. This notable population of black holes evaded detection in previous observational studies, which used the radial velocity method or looked for radio and X-ray emission from material falling onto black holes.
This new discovery features a different approach, known as astrometry, to measure very small movements of stars over time. By sifting through more than 20 years of Hubble archival data and pulling in recent Webb data to further refine their astrometric measurements, the team located a star orbiting an invisible object so hefty that it has to be a black hole. Dubbed oMEGACat BH-2, it is the first stellar-mass black hole detected in Omega Centauri, and it has some surprising qualities. oMEGACat BH-2 has a lower-than-expected mass and, with its visible star companion, the black hole-star duo has the longest orbital period of any black hole binary system known to date.
“With Hubble and Webb data, we were able to see the motion of the visible main sequence star that is part of this binary, which is about 18,000 light-years away in the dense environment of Omega Centauri,” said Matthew Whitaker of the University of Utah, Salt Lake City, lead author of the paper. “The precision of these measurements is incredible, down to a fraction of a pixel on Hubble and Webb’s detectors. It would not have been possible to find this black hole without these two space telescopes.”
Astronomers found Omega Centauri’s first stellar-mass black hole, which has a visible star companion that is shown in greater detail. They used 20-plus years of data from NASA’s Hubble Space Telescope and recent data from NASA’s James Webb Space Telescope to make the discovery.
Image: ESA, NASA, Maximilian Häberle (MPIA), Joseph DePasquale (STScI)
The team’s findings refine a past study by a different group of scientists that suggested this binary system included a neutron star. By expanding Hubble data from the earlier investigation with archival Hubble astrometric measurements from 2002 to 2023, and pulling in Webb near-infrared data to improve precision, the University of Utah-led team was able to better constrain the mass of the visible star’s dark companion, ruling out the neutron star possibility.
“While we already knew that the star was 0.78 solar masses, we can now calculate the black hole’s mass, which is 4.46 solar masses and therefore too heavy to be a neutron star. However, its mass is much lower than would be expected in a metal-poor environment like Omega Centauri. This is surprising and exciting,” said Anil Seth of the University of Utah, a coauthor of the study. “We now know that a metal-poor star is able to form a black hole like this, and we need to figure out how that happens. This detection is providing some data to those who do that kind of modeling.”
Long time coming
Based on the precise data from Hubble and Webb, the team could chart the star’s path over 20-plus years, during its closest approach to its black hole companion when it moved the fastest across the sky. From the extensive data, the team determined that the visible star orbits oMEGACat BH-2 once every 94 years, making it the longest-period black hole binary ever known.
Its long orbital period also gives a clue to the origin of this binary system. It was probably dynamically formed, meaning the star and its black hole companion did not start out together but rather found each other in this cluster. The researchers calculated that a system like oMEGACat BH-2 will survive for less than a billion years before it is torn apart by encounters with nearby stars, a much shorter span than the age of the cluster (approximately 12 billion years old).
“It’s important to understand black hole populations in globular clusters because there’s uncertainty about their physics and formation,” said Seth. “More specifically, understanding the process of forming black holes and then dynamically forming binaries is vital, because it affects our ability to interpret and understand gravitational wave events. Environments like Omega Centauri are the primary places where we think binaries are merging and creating these waves.”
The team’s discovery of stellar-mass black hole oMEGACat BH-2 with the Hubble-Webb dataset is just the start of finding these evasive black hole populations in globular star clusters.
“With Hubble and Webb, we can continue to look at Omega Centauri and expand our search for similar systems within other clusters,” said Whitaker. “We’re also very excited for the launch of NASA’s Nancy Grace Roman Space Telescope because it will image the crowded galactic bulge, including the galactic center, very regularly with Hubble-like resolution and with a much wider field of view. We’re hoping we’ll be able to find black hole binary systems like this one because of the regular cadence of Roman’s observations.”
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
Astronomers found Omega Centauri’s first stellar-mass black hole, which has a visible star companion that is shown in greater detail. They used 20-plus years of data from NASA’s Hubble Space Telescope and recent data from NASA’s James Webb Space Telescope to make the discovery.
Star Orbiting Black Hole Animation
The precise data collected by NASA’s Hubble and James Webb space telescopes enabled a team of astronomers to chart the visible star’s orbital path over a 20 year-plus period.
Rusting rivers occur across the Brooks Range in northern Alaska, as shown in this map based on in situ and satellite observations from 2007-2024.
NASA Earth Observatory/Michala Garrison
From declines in annual sea ice extent to the greening of the tundra, environmental change has been unfolding incrementally in the Arctic over decades. Some shifts, however, have come on more abruptly.
Satellite, aerial, and ground-based surveys spanning more than 600 miles (1,000 kilometers) across Alaska’s Brooks Range have observed stream water changing from clear to orange in more than 200 watersheds. What’s more, scientists are finding that the switch has largely taken place within the past 10 to 12 years, coinciding with a pronounced increase in air and ground temperatures.
Thawing permafrost soils, accelerated by warming air and ground temperatures, are the most likely cause of the “rusty” rivers, scientists say. They surmise that water is now encountering thawed ground and bedrock where it previously had not. Chemical weathering of minerals leaches iron, sulfuric acid, and trace metals into streams, akin to the process behind acid mine drainage, which similarly pollutes and discolors water near abandoned mines. Microbes may also contribute to the color change by producing a soluble form of iron as they digest plant and animal matter in thawing soils, which then becomes oxygenated, or “rusts,” in flowing streams.
Researchers have only recently begun to comprehend the prevalence of rusting rivers in Arctic regions. In 2024, a team of National Park Service, U.S. Geological Survey, and university scientists documented 75 northern Alaskan streams that recently changed from clear to orange. With subsequent exploration, mostly using high-resolution satellite imagery, they added 200 more observations. The locations of these discolored streams, published in NOAA’s 2025 Arctic Report Card, are shown in the map above.
“I’m still surprised by the broad spatial scope of our observations,” said Brett Poulin, environmental toxicologist at the University of California, Davis. He and his collaborators have been monitoring the region’s streams since 2013—when many were still clear. “Now we’re seeing hundreds of streams that have changed color seemingly overnight, including in designated National Wild & Scenic River corridors,” he said.
2017
2020
NASA Earth Observatory/Michala Garrison
NASA Earth Observatory/Michala Garrison
NASA Earth Observatory/Michala Garrison
NASA Earth Observatory/Michala Garrison
2017
2020
The Agashashok River in Noatak National Preserve is one of many streams in Alaska whose water has turned from clear to rusty orange. The change appears in these images, acquired on July 12, 2017 (left), and July 20, 2020 (right), by the OLI (Operational Land Imager) on Landsat 8. NASA Earth Observatory images by Michala Garrison.
Observations from NASA/USGS Landsat satellites allowed the team to determine the timing of several of these changes. For the 2024 study led by ecologist Jon O’Donnell of the National Park Service, the team calculated a redness index based on red and blue spectral information sensitive to the color of iron hydroxides (i.e., rust) in water. After analyzing a subset of streams, they found that some turned rusty around 2018 and stayed that way, while others had periods of rusting and then returned to being clear.
One stream that underwent a sudden change is the Agashashok River in Noatak National Preserve (above). In 2019, a jump in redness values appeared in Landsat data along this waterway. Ground and aerial surveys the same year found an orange section of the river several kilometers long, and vegetation around nearby groundwater seeps and springs appeared blackened. “The Landsat archive has proved uniquely useful for investigating the historical onset of rusting rivers where creeks and rivers are sufficiently large,” Poulin said.
Having gained a better picture of the extent and timing of the phenomenon, the researchers want to focus on the conditions driving the orange color’s onset and the yearly and seasonal changes. A deep snowpack may play a role some years, for example, by insulating the soil from cold winter temperatures and enabling permafrost thaw earlier in the summer. In addition, periods of higher streamflow throughout the year can dilute the discoloration. The team is planning a geophysical survey along a hillslope where acidic groundwater is discharging to the surface to investigate the subsurface geology, hydrology, and permafrost.
Further, they seek to quantify the effects on water quality and aquatic ecosystems. Communities rely on these river systems for drinking water and subsistence fisheries, and a decrease in stream biodiversity has already been documented in some locations coincident with water turning orange. The researchers now are looking deeper into the patterns of toxicity over time and space, such as where rusting rivers overlap with known spawning areas for migratory fish.
“The rusting river phenomenon is a good example of an unforeseen consequence of permafrost thaw in the Arctic,” Poulin said. “Further, it’s consistent with the emergence of acid rock drainage following cryosphere loss across Earth.”
NASA Earth Observatory images by Michala Garrison, using stream location data from O’Donnell, J.A., et al., and Landsat data from the U.S. Geological Survey. Story by Lindsey Doermann.
Downloads
2007-2024
JPEG (2.16 MB)
July 12, 2017
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July 20, 2020
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References & Resources
NASA Earth Observatory (2024, January 16) Rusting Rivers. Accessed July 9, 2026.
The Zooniverse, a NASA grantee that runs the world’s largest platform for online people-powered research, has reached an extraordinary milestone: 1 billion classifications contributed by volunteers around the world. This milestone is a celebration of everyone who has marked a dip in a light curve, confirmed the presence of a moving object in a short video, or identified species in a camera trap image. Each of these small contributions collectively advances our understanding of the universe.
A total of 31 NASA-sponsored citizen science projects have been hosted on Zooniverse, accounting for 120 million classifications by 324 thousand volunteers since 2020. Through projects like Planet Hunters TESS, Daily Minor Planet, Backyard Worlds: Planet 9, Space Umbrella, and Snapshot Wisconsin, volunteers help discover exoplanets, identify near-Earth objects and asteroids, search for brown dwarfs and planetary systems, analyze effects of the solar wind, and inform wildlife management decisions. These projects have led to 96 scientific publications, and 56 of these articles feature NASA citizen scientists as co-authors to recognize the significance of their research contributions. These efforts demonstrate how public participation can accelerate discovery by combining human curiosity and pattern recognition with data from NASA missions and observatories. Collaboration between volunteers, scientists, and computing technology will be even more important in the future as we tackle enormous and complex datasets, like those from NASA’s upcoming Nancy Grace Roman Space Telescope.
“One billion classifications represent far more than a number; it’s one billion moments of curiosity transformed into meaningful contributions to research,” said Laura Trouille, principal investigator of Zooniverse and vice president of Science Engagement at the Adler Planetarium. “Every classification on Zooniverse brings us one step closer to new discoveries and a deeper understanding of our universe, our world, and ourselves.”
Zooniverse is the world’s largest platform for people-powered research. Co-founded by the Adler Planetarium and the University of Oxford, with the University of Minnesota serving as a key institutional partner, Zooniverse enables anyone, anywhere to contribute directly to real scientific research. Through its six-year collaboration with NASA, Zooniverse provides science-enabling infrastructure to NASA researchers through tools and a community of more than 3 million registered volunteers.
Ground displacement was especially intense near Caracas and La Guaira, Venezuela, after earthquakes struck the region on June 24, 2026. The map was derived from NISAR (NASA-ISRO Synthetic Aperture Radar) data acquired on June 25 and June 30 (after the earthquakes) and June 13 and June 18 (before the earthquakes).
NASA Earth Observatory/Lauren Dauphin
On June 24, 2026, a magnitude 7.2 earthquake struck northern Venezuela, followed under a minute later by a magnitude 7.5 mainshock. Together, the quakes left immense damage and loss of life across the region. In the days that followed, satellite-based maps of ground displacement revealed how the land surface moved, providing insight into the forces behind the severe destruction in locations such as La Guaira and other coastal cities in La Guaira state.
This map was produced using data from the NISAR (NASA-ISRO Synthetic Aperture Radar) satellite and processed by the NISAR science team at NASA’s Jet Propulsion Laboratory (JPL). Scientists used a technique called InSAR, which compares data from repeat passes to detect subtle changes in the distance between the satellite and the ground. Images acquired on June 25 and June 30, after the quakes, were compared with images from June 13 and June 18, before the quakes.
NISAR views Earth at an angle, about 40 degrees from straight down, allowing it to capture a mix of horizontal and vertical displacement. In this map, red areas show where the ground moved east and up; blue areas moved west and down. Because the earthquake occurred on a strike-slip fault, however, most of the displacement shown in this map was horizontal (east and west).
White areas indicate little to no land displacement, including a thin strip near the middle-left of the scene, close to Morón, marking roughly where the fault ruptured at depth. The fault is part of a network of fractures that lies along the boundary between the Caribbean plate to the north and the South American plate to the south. Scientists say faults along this plate boundary, including the San Sebastián fault system where these quakes likely occurred (and possibly part of the Boconó system), have long been accumulating strain.
The fault rupture propagated offshore, toward the east, and then back onshore near the international airport north of Caracas, marked by the narrow white band visible between westward and eastward displacement. Just south of this fault section, the deep blue color indicates that the westward surface displacement along this part of the fault was far greater than elsewhere, reaching as much as 60 centimeters (24 inches).
“These are reasons why the damage in Caracas and La Guaira was so extreme,” said Eric Fielding, a geophysicist at JPL who provided the maps. “InSAR tells us a lot about what happened during this earthquake.”
Using the NISAR data, the U.S. Geological Survey refined its fault-slip model, or “finite fault model,” to better constrain how the fault slipped at depth, including along the rupture’s eastern section. “That is extremely helpful for the people who need to understand why damage was so severe in that area,” Fielding said.
The displacement maps for this event were provided through NISAR’s Urgent Response (UR) system, a fast-track process that can deliver data within 12 to 24 hours to support disaster response. The rapid processing relies on predicted orbit information, so UR maps are preliminary until they are later reprocessed with precise orbit information, typically within a day or two. This marks the first time the NISAR UR system has been used to map surface displacement from a large earthquake.
NASA Earth Observatory map by Lauren Dauphin, using data provided Eric Fielding and processed by the NISAR science team at NASA’s Jet Propulsion Laboratory (JPL). Story by Kathryn Hansen.
Downloads
June 25 & June 30, 2026
JPEG (3.51 MB)
References & Resources
NASA (2025, July 23) Interferometry. Accessed July 9, 2026.
