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The Universe is Expanding Faster These Days and Dark Energy is Responsible. So What is Dark Energy?
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By NASA
A funky effect Einstein predicted, known as gravitational lensing — when a foreground galaxy magnifies more distant galaxies behind it — will soon become common when NASA’s Nancy Grace Roman Space Telescope begins science operations in 2027 and produces vast surveys of the cosmos.
This image shows a simulated observation from NASA’s Nancy Grace Roman Space Telescope with an overlay of its Wide Field Instrument’s field of view. More than 20 gravitational lenses, with examples shown at left and right, are expected to pop out in every one of Roman’s vast observations. A journal paper led by Bryce Wedig, a graduate student at Washington University in St. Louis, Missouri, estimates that of those Roman detects, about 500 from the telescope’s High-Latitude Wide-Area Survey will be suitable for dark matter studies. By examining such a large population of gravitational lenses, the researchers hope to learn a lot more about the mysterious nature of dark matter.Credit: NASA, Bryce Wedig (Washington University), Tansu Daylan (Washington University), Joseph DePasquale (STScI) A particular subset of gravitational lenses, known as strong lenses, is the focus of a new paper published in the Astrophysical Journal led by Bryce Wedig, a graduate student at Washington University in St. Louis. The research team has calculated that over 160,000 gravitational lenses, including hundreds suitable for this study, are expected to pop up in Roman’s vast images. Each Roman image will be 200 times larger than infrared snapshots from NASA’s Hubble Space Telescope, and its upcoming “wealth” of lenses will vastly outpace the hundreds studied by Hubble to date.
Roman will conduct three core surveys, providing expansive views of the universe. This science team’s work is based on a previous version of Roman’s now fully defined High-Latitude Wide-Area Survey. The researchers are working on a follow-up paper that will align with the final survey’s specifications to fully support the research community.
“The current sample size of these objects from other telescopes is fairly small because we’re relying on two galaxies to be lined up nearly perfectly along our line of sight,” Wedig said. “Other telescopes are either limited to a smaller field of view or less precise observations, making gravitational lenses harder to detect.”
Gravitational lenses are made up of at least two cosmic objects. In some cases, a single foreground galaxy has enough mass to act like a lens, magnifying a galaxy that is almost perfectly behind it. Light from the background galaxy curves around the foreground galaxy along more than one path, appearing in observations as warped arcs and crescents. Of the 160,000 lensed galaxies Roman may identify, the team expects to narrow that down to about 500 that are suitable for studying the structure of dark matter at scales smaller than those galaxies.
“Roman will not only significantly increase our sample size — its sharp, high-resolution images will also allow us to discover gravitational lenses that appear smaller on the sky,” said Tansu Daylan, the principal investigator of the science team conducting this research program. Daylan is an assistant professor and a faculty fellow at the McDonnell Center for the Space Sciences at Washington University in St. Louis. “Ultimately, both the alignment and the brightness of the background galaxies need to meet a certain threshold so we can characterize the dark matter within the foreground galaxies.”
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This video shows how a background galaxy’s light is lensed or magnified by a massive foreground galaxy, seen at center, before reaching NASA’s Roman Space Telescope. Light from the background galaxy is distorted, curving around the foreground galaxy and appearing more than once as warped arcs and crescents. Researchers studying these objects, known as gravitational lenses, can better characterize the mass of the foreground galaxy, which offers clues about the particle nature of dark matter.Credit: NASA, Joseph Olmsted (STScI) What Is Dark Matter?
Not all mass in galaxies is made up of objects we can see, like star clusters. A significant fraction of a galaxy’s mass is made up of dark matter, so called because it doesn’t emit, reflect, or absorb light. Dark matter does, however, possess mass, and like anything else with mass, it can cause gravitational lensing.
When the gravity of a foreground galaxy bends the path of a background galaxy’s light, its light is routed onto multiple paths. “This effect produces multiple images of the background galaxy that are magnified and distorted differently,” Daylan said. These “duplicates” are a huge advantage for researchers — they allow multiple measurements of the lensing galaxy’s mass distribution, ensuring that the resulting measurement is far more precise.
Roman’s 300-megapixel camera, known as its Wide Field Instrument, will allow researchers to accurately determine the bending of the background galaxies’ light by as little as 50 milliarcseconds, which is like measuring the diameter of a human hair from the distance of more than two and a half American football fields or soccer pitches.
The amount of gravitational lensing that the background light experiences depends on the intervening mass. Less massive clumps of dark matter cause smaller distortions. As a result, if researchers are able to measure tinier amounts of bending, they can detect and characterize smaller, less massive dark matter structures — the types of structures that gradually merged over time to build up the galaxies we see today.
With Roman, the team will accumulate overwhelming statistics about the size and structures of early galaxies. “Finding gravitational lenses and being able to detect clumps of dark matter in them is a game of tiny odds. With Roman, we can cast a wide net and expect to get lucky often,” Wedig said. “We won’t see dark matter in the images — it’s invisible — but we can measure its effects.”
“Ultimately, the question we’re trying to address is: What particle or particles constitute dark matter?” Daylan added. “While some properties of dark matter are known, we essentially have no idea what makes up dark matter. Roman will help us to distinguish how dark matter is distributed on small scales and, hence, its particle nature.”
Preparations Continue
Before Roman launches, the team will also search for more candidates in observations from ESA’s (the European Space Agency’s) Euclid mission and the upcoming ground-based Vera C. Rubin Observatory in Chile, which will begin its full-scale operations in a few weeks. Once Roman’s infrared images are in hand, the researchers will combine them with complementary visible light images from Euclid, Rubin, and Hubble to maximize what’s known about these galaxies.
“We will push the limits of what we can observe, and use every gravitational lens we detect with Roman to pin down the particle nature of dark matter,” Daylan said.
The Nancy Grace Roman Space Telescope is managed at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, with participation by NASA’s Jet Propulsion Laboratory in Southern California; Caltech/IPAC in Pasadena, California; the Space Telescope Science Institute in Baltimore; and a science team comprising scientists from various research institutions. The primary industrial partners are BAE Systems, Inc. in Boulder, Colorado; L3Harris Technologies in Melbourne, Florida; and Teledyne Scientific & Imaging in Thousand Oaks, California.
By Claire Blome
Space Telescope Science Institute, Baltimore, Md.
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Last Updated Jun 12, 2025 EditorAshley BalzerContactAshley Balzerashley.m.balzer@nasa.govLocationNASA Goddard Space Flight Center Related Terms
Nancy Grace Roman Space Telescope Astrophysics Dark Matter Galaxies Galaxies, Stars, & Black Holes Galaxies, Stars, & Black Holes Research The Universe Explore More
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By USH
The photograph was captured by the Mast Camera (Mastcam) aboard NASA’s Curiosity rover on Sol 3551 (August 2, 2022, at 20:43:28 UTC).
What stands out in the image are two objects, that appear strikingly out of place amid the natural Martian landscape of rocks and boulders. Their sharp edges, right angles, flat surfaces, and geometric symmetry suggest they may have been shaped by advanced cutting tools rather than natural erosion.
Could these ancient remnants be part of a destroyed structure or sculpture? If so, they may serve as yet another piece of evidence pointing to the possibility that Mars was once home to an intelligent civilization, perhaps even the advanced humanoid beings who, according to some theories, fled the catastrophic destruction of planet Maldek and sought refuge on the Red Planet.
Objects discovered by Jean Ward Watch Jean Ward's YouTube video on this topic: HereSee original NASA source: Here
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By Space Force
Summer is the time to enjoy the warm sunny days with family and friends but do it safely and never leave Mother Nature to chance and prepare for the unexpected.
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By NASA
Explore This Section Science Science Activation Take a Tour of the Cosmos with… Overview Learning Resources Science Activation Teams SME Map Opportunities More Science Activation Stories Citizen Science 4 min read
Take a Tour of the Cosmos with New Interactives from NASA’s Universe of Learning
Ready for a tour of the cosmos? NASA’s Universe of Learning has released a new, dynamic way for lifelong learners to explore NASA’s breathtaking images of the universe—ViewSpace interactive Image Tours. ViewSpace has an established track record of providing museums, science centers, libraries, and other informal learning environments with free, web-based videos and digital interactives—like its interactive Image Sliders. These new Image Tours are another unique experience from NASA’s Universe of Learning, created through a collaboration between scientists that operate NASA telescopes and experts well-versed in the most modern methods of learning. Hands-on, self-directed learning resources like these have long been valued by informal learning sites as effective means for engaging and intriguing users with the latest discoveries from NASA’s space telescope missions—while encouraging lifelong learners to continue their passionate exploration of the stars, galaxies, and distant worlds.
With these new ViewSpace Image Tours, visitors can take breathtaking journeys through space images that contain many exciting stories. The “Center of the Milky Way Galaxy” Tour, for example, uses breathtaking images from NASA’s Hubble, Spitzer, and Chandra X-ray telescopes and includes eleven Tour Stops, where users can interact with areas like “the Brick”—a dense, dark cloud of hydrogen molecules imaged by Spitzer. Another Tour Stop zooms toward the supermassive black hole, Sagittarius A*, offering a dramatic visual journey to the galaxy’s core.
In other tours, like the “Herbig-Haro 46/47” Tour, learners can navigate through points of interest in an observation from a single telescope mission. In this case, NASA’s James Webb Space Telescope provides the backdrop where lifelong learners can explore superheated jets of gas and dust being ejected at tremendous speeds from a pair of young, forming stars. The power of Webb turns up unexpected details in the background, like a noteworthy distant galaxy famous for its uncanny resemblance to a question mark. Each Interactive Image Tour allows people to examine unique features through videos, images, or graphical overlays to identify how those features have formed in ways that static images alone can’t convey.
These tours, which include detailed visual descriptions for each Tour Stop, illuminate the science behind the beauty, allowing learners of all ages to develop a greater understanding of and excitement for space science, deepening their engagement with astronomy, regardless of their prior experience. Check out the About the Interactives page on the ViewSpace website for a detailed overview of how to use the Image Tours.
ViewSpace currently offers three Image Tours, and the collection will continue growing:
Center of the Milky Way Galaxy:
Peer through cosmic dust and uncover areas of intense activity near the Milky Way’s core, featuring imagery from the Hubble Space Telescope, Spitzer Space Telescope, and the Chandra X-ray Observatory.
Herbig-Haro 46/47:
Witness how a tightly bound pair of young stars shapes their nebula through ejections of gas and dust in an image from the James Webb Space Telescope.
The Whirlpool Galaxy:
Explore the iconic swirling arms and glowing core of a stunning spiral galaxy, with insights into star formation, galaxy structure, and more in a Hubble Space Telescope image.
“The Image Tours are beautiful, dramatic, informational, and easy to use,” explained Sari Custer, Chief of Science and Curiosity at Arizona Science Center. “I’m excited to implement them in my museum not only because of the incredible images and user-friendly features, but also for the opportunity to excite and ignite the public’s curiosity about space.”
NASA’s Universe of Learning is supported by NASA under cooperative agreement award number NNX16AC65A and is part of NASA’s Science Activation Portfolio. Learn more about how Science Activation connects NASA science experts, real content, and experiences with community leaders to do science in ways that activate minds and promote deeper understanding of our world and beyond: https://science.nasa.gov/learn/about-science-activation/
Select views from various Image Tours. Clockwise from top left: The Whirlpool Galaxy, Center of the Milky Way Galaxy, Herbig-Haro 46/47, detail view in the Center of the Milky Way Galaxy. Share
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Last Updated May 13, 2025 Editor NASA Science Editorial Team Related Terms
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By NASA
Did you know some of the brightest sources of light in the sky come from the regions around black holes in the centers of galaxies? It sounds a little contradictory, but it’s true! They may not look bright to our eyes, but satellites have spotted oodles of them across the universe.
One of those satellites is NASA’s Fermi Gamma-ray Space Telescope. Fermi has found thousands of these kinds of galaxies since it launched in 2008, and there are many more out there!
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Watch a cosmic gamma-ray fireworks show in this animation using just a year of data from the Large Area Telescope (LAT) aboard NASA’s Fermi Gamma-ray Space Telescope. Each object’s magenta circle grows as it brightens and shrinks as it dims. The yellow circle represents the Sun following its apparent annual path across the sky. The animation shows a subset of the LAT gamma-ray records available for more than 1,500 objects in a continually updated repository. Over 90% of these sources are a type of galaxy called a blazar, powered by the activity of a supermassive black hole. NASA’s Marshall Space Flight Center/Daniel Kocevski Black holes are regions of space that have so much gravity that nothing — not light, not particles, nada — can escape. Most galaxies have supermassive black holes at their centers, and these black holes are hundreds of thousands to billions of times the mass of our Sun. In active galactic nuclei (also called “AGN” for short, or just “active galaxies”) the central region is stuffed with gas and dust that’s constantly falling toward the black hole. As the gas and dust fall, they start to spin and form a disk. Because of the friction and other forces at work, the spinning disk starts to heat up.
This composite view of the active galaxy Markarian 573 combines X-ray data (blue) from NASA’s Chandra X-ray Observatory and radio observations (purple) from the Karl G. Jansky Very Large Array in New Mexico with a visible light image (gold) from the Hubble Space Telescope. Markarian 573 is an active galaxy that has two cones of emission streaming away from the supermassive black hole at its center. X-ray: NASA/CXC/SAO/A.Paggi et al; Optical: NASA/STScI; Radio: NSF/NRAO/VLA The disk’s heat gets emitted as light, but not just wavelengths of it that we can see with our eyes. We detect light from AGN across the entire electromagnetic spectrum, from the more familiar radio and optical waves through to the more exotic X-rays and gamma rays, which we need special telescopes to spot.
In the heart of an active galaxy, matter falling toward a supermassive black hole creates jets of particles traveling near the speed of light as shown in this artist’s concept. NASA/Goddard Space Flight Center Conceptual Image Lab About one in 10 AGN beam out jets of energetic particles, which are traveling almost as fast as light. Scientists are studying these jets to try to understand how black holes — which pull everything in with their huge amounts of gravity — somehow provide the energy needed to propel the particles in these jets.
This artist’s concept shows two views of the active galaxy TXS 0128+554, located around 500 million light-years away. Left: The galaxy’s central jets appear as they would if we viewed them both at the same angle. The black hole, embedded in a disk of dust and gas, launches a pair of particle jets traveling at nearly the speed of light. Scientists think gamma rays (magenta) detected by NASA’s Fermi Gamma-ray Space Telescope originate from the base of these jets. As the jets collide with material surrounding the galaxy, they form identical lobes seen at radio wavelengths (orange). The jets experienced two distinct bouts of activity, which created the gap between the lobes and the black hole. Right: The galaxy appears in its actual orientation, with its jets tipped out of our line of sight by about 50 degrees. NASA’s Goddard Space Flight Center Many of the ways we tell one type of AGN from another depend on how they’re oriented from our point of view. With radio galaxies, for example, we see the jets from the side as they’re beaming vast amounts of energy into space. Then there’s blazars, which are a type of AGN that have a jet that is pointed almost directly at Earth, which makes the AGN particularly bright.
Blazar 3C 279’s historic gamma-ray flare in 2015 can be seen in this image from the Large Area Telescope on NASA’s Fermi satellite. During the flare, the blazar outshone the Vela pulsar, usually the brightest object in the gamma-ray sky. NASA/DOE/Fermi LAT Collaboration Fermi has been searching the sky for gamma ray sources since 2008. More than half of the sources it has found have been blazars. Gamma rays are useful because they can tell us a lot about how particles accelerate and how they interact with their environment.
So why do we care about AGN? We know that some AGN formed early in the history of the universe. With their enormous power, they almost certainly affected how the universe changed over time. By discovering how AGN work, we can understand better how the universe came to be the way it is now.
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Last Updated Apr 30, 2025 Related Terms
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