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By NASA
Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts Multimedia Images Videos Sonifications Podcasts e-Books Online Activities 3D Hubble Models Lithographs Fact Sheets Posters Hubble on the NASA App Glossary News Hubble News Social Media Media Resources More 35th Anniversary Online Activities 2 min read
Hubble Studies Small but Mighty Galaxy
This NASA/ESA Hubble Space Telescope features the nearby galaxy NGC 4449. ESA/Hubble & NASA, E. Sabbi, D. Calzetti, A. Aloisi This portrait from the NASA/ESA Hubble Space Telescope puts the nearby galaxy NGC 4449 in the spotlight. The galaxy is situated just 12.5 million light-years away in the constellation Canes Venatici (the Hunting Dogs). It is a member of the M94 galaxy group, which is near the Local Group of galaxies that the Milky Way is part of.
NGC 4449 is a dwarf galaxy, which means that it is far smaller and contains fewer stars than the Milky Way. But don’t let its small size fool you — NGC 4449 packs a punch when it comes to making stars! This galaxy is currently forming new stars at a much faster rate than expected for its size, which makes it a starburst galaxy. Most starburst galaxies churn out stars mainly in their centers, but NGC 4449 is alight with brilliant young stars throughout. Researchers believe that this global burst of star formation came about because of NGC 4449’s interactions with its galactic neighbors. Because NGC 4449 is so close, it provides an excellent opportunity for Hubble to study how interactions between galaxies can influence the formation of new stars.
Hubble released an image of NGC 4449 in 2007. This new version incorporates several additional wavelengths of light that Hubble collected for multiple observing programs. These programs encompass an incredible range of science, from a deep dive into NGC 4449’s star-formation history to the mapping of the brightest, hottest, and most massive stars in more than two dozen nearby galaxies.
The NASA/ESA/CSA James Webb Space Telescope has also observed NGC 4449, revealing in intricate detail the galaxy’s tendrils of dusty gas, glowing from the intense starlight radiated by the flourishing young stars.
Text Credit: ESA/Hubble
Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contact:
Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
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Last Updated Jun 20, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
Hubble Space Telescope Astrophysics Astrophysics Division Galaxies Goddard Space Flight Center Irregular Galaxies The Universe Keep Exploring Discover More Topics From Hubble
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Hubble’s Galaxies
Galaxy Details and Mergers
Hubble’s Night Sky Challenge
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By NASA
This NASA/ESA Hubble Space Telescope image features the barred spiral galaxy IC 758.ESA/Hubble & NASA, C. Kilpatrick This serene spiral galaxy hides a cataclysmic past. The galaxy IC 758, shown in this NASA/ESA Hubble Space Telescope image, is situated 60 million light-years away in the constellation Ursa Major.
Hubble captured this image in 2023. IC 758 appears peaceful, with its soft blue spiral arms curving gently around its hazy barred center. However, in 1999, astronomers spotted a powerful explosion in this galaxy. The supernova SN 1999bg marked the dramatic end of a star far more massive than the Sun.
Researchers do not know exactly how massive this star was before it exploded, but will use these Hubble observations to measure the masses of stars in SN 1999bg’s neighborhood. These measurements will help them estimate the mass of the star that went supernova. The Hubble data may also reveal whether SN 1999bg’s progenitor star had a companion, which would provide additional clues about the star’s life and death.
A supernova represents more than just the demise of a single star — it’s also a powerful force that can shape its neighborhood. When a massive star collapses, triggering a supernova, its outer layers rebound off its shrunken core. The explosion stirs the interstellar soup of gas and dust out of which new stars form. This interstellar shakeup can scatter and heat nearby gas clouds, preventing new stars from forming, or it can compress them, creating a burst of new star formation. The cast-off layers enrich the interstellar medium, from which new stars form, with heavy elements manufactured in the core of the supernova.
Text Credit: ESA/Hubble
Image Credit: ESA/Hubble & NASA, C. Kilpatrick
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By NASA
Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts Multimedia Images Videos Sonifications Podcasts e-Books Online Activities 3D Hubble Models Lithographs Fact Sheets Posters Hubble on the NASA App Glossary News Hubble News Social Media Media Resources More 35th Anniversary Online Activities 2 min read
Hubble Studies a Spiral’s Supernova Scene
This NASA/ESA Hubble Space Telescope image features the barred spiral galaxy IC 758. ESA/Hubble & NASA, C. Kilpatrick This serene spiral galaxy hides a cataclysmic past. The galaxy IC 758, shown in this NASA/ESA Hubble Space Telescope image, is situated 60 million light-years away in the constellation Ursa Major.
Hubble captured this image in 2023. IC 758 appears peaceful, with its soft blue spiral arms curving gently around its hazy barred center. However, in 1999, astronomers spotted a powerful explosion in this galaxy. The supernova SN 1999bg marked the dramatic end of a star far more massive than the Sun.
Researchers do not know exactly how massive this star was before it exploded, but will use these Hubble observations to measure the masses of stars in SN 1999bg’s neighborhood. These measurements will help them estimate the mass of the star that went supernova. The Hubble data may also reveal whether SN 1999bg’s progenitor star had a companion, which would provide additional clues about the star’s life and death.
A supernova represents more than just the demise of a single star — it’s also a powerful force that can shape its neighborhood. When a massive star collapses, triggering a supernova, its outer layers rebound off its shrunken core. The explosion stirs the interstellar soup of gas and dust out of which new stars form. This interstellar shakeup can scatter and heat nearby gas clouds, preventing new stars from forming, or it can compress them, creating a burst of new star formation. The cast-off layers enrich the interstellar medium, from which new stars form, with heavy elements manufactured in the core of the supernova.
Text Credit: ESA/Hubble
Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contact:
Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
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Last Updated Jun 13, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
Hubble Space Telescope Astrophysics Astrophysics Division Galaxies Goddard Space Flight Center Spiral Galaxies The Universe Keep Exploring Discover More Topics From Hubble
Hubble Space Telescope
Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
Hubble’s Galaxies
Homing in on Cosmic Explosions
Hubble’s Night Sky Challenge
View the full article
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By NASA
5 min read
NASA Launching Rockets Into Radio-Disrupting Clouds
NASA is launching rockets from a remote Pacific island to study mysterious, high-altitude cloud-like structures that can disrupt critical communication systems. The mission, called Sporadic-E ElectroDynamics, or SEED, opens its three-week launch window from Kwajalein Atoll in the Marshall Islands on Friday, June 13.
The atmospheric features SEED is studying are known as Sporadic-E layers, and they create a host of problems for radio communications. When they are present, air traffic controllers and marine radio users may pick up signals from unusually distant regions, mistaking them for nearby sources. Military operators using radar to see beyond the horizon may detect false targets — nicknamed “ghosts” — or receive garbled signals that are tricky to decipher. Sporadic-E layers are constantly forming, moving, and dissipating, so these disruptions can be difficult to anticipate.
An animated illustration depicts Sporadic-E layers forming in the lower portions of the ionosphere, causing radio signals to reflect back to Earth before reaching higher layers of the ionosphere. NASA’s Goddard Space Flight Center/Conceptual Image Lab Sporadic-E layers form in the ionosphere, a layer of Earth’s atmosphere that stretches from about 40 to 600 miles (60 to 1,000 kilometers) above sea level. Home to the International Space Station and most Earth-orbiting satellites, the ionosphere is also where we see the greatest impacts of space weather. Primarily driven by the Sun, space weather causes myriad problems for our communications with satellites and between ground systems. A better understanding of the ionosphere is key to keeping critical infrastructure running smoothly.
The ionosphere is named for the charged particles, or ions, that reside there. Some of these ions come from meteors, which burn up in the atmosphere and leave traces of ionized iron, magnesium, calcium, sodium, and potassium suspended in the sky. These “heavy metals” are more massive than the ionosphere’s typical residents and tend to sink to lower altitudes, below 90 miles (140 kilometers). Occasionally, they clump together to create dense clusters known as Sporadic-E layers.
The Perseids meteor shower peaks in mid-August. Meteors like these can deposit metals into Earth’s ionosphere that can help create cloud-like structures called Sporadic-E layers. NASA/Preston Dyches “These Sporadic-E layers are not visible to naked eye, and can only be seen by radars. In the radar plots, some layers appear like patchy and puffy clouds, while others spread out, similar to an overcast sky, which we call blanketing Sporadic-E layer” said Aroh Barjatya, the SEED mission’s principal investigator and a professor of engineering physics at Embry-Riddle Aeronautical University in Daytona Beach, Florida. The SEED team includes scientists from Embry-Riddle, Boston College in Massachusetts, and Clemson University in South Carolina.
“There’s a lot of interest in predicting these layers and understanding their dynamics because of how they interfere with communications,” Barjatya said.
A Mystery at the Equator
Scientists can explain Sporadic-E layers when they form at midlatitudes but not when they appear close to Earth’s equator — such as near Kwajalein Atoll, where the SEED mission will launch.
In the Northern and Southern Hemispheres, Sporadic-E layers can be thought of as particle traffic jams.
Think of ions in the atmosphere as miniature cars traveling single file in lanes defined by Earth’s magnetic field lines. These lanes connect Earth end to end — emerging near the South Pole, bowing around the equator, and plunging back into the North Pole.
A conceptual animation shows Earth’s magnetic field. The blue lines radiating from Earth represent the magnetic field lines that charged particles travel along. NASA’s Goddard Space Flight Center/Conceptual Image Lab At Earth’s midlatitudes, the field lines angle toward the ground, descending through atmospheric layers with varying wind speeds and directions. As the ions pass through these layers, they experience wind shear — turbulent gusts that cause their orderly line to clump together. These particle pileups form Sporadic-E layers.
But near the magnetic equator, this explanation doesn’t work. There, Earth’s magnetic field lines run parallel to the surface and do not intersect atmospheric layers with differing winds, so Sporadic-E layers shouldn’t form. Yet, they do — though less frequently.
“We’re launching from the closest place NASA can to the magnetic equator,” Barjatya said, “to study the physics that existing theory doesn’t fully explain.”
Taking to the Skies
To investigate, Barjatya developed SEED to study low-latitude Sporadic-E layers from the inside. The mission relies on sounding rockets — uncrewed suborbital spacecraft carrying scientific instruments. Their flights last only a few minutes but can be launched precisely at fleeting targets.
Beginning the night of June 13, Barjatya and his team will monitor ALTAIR (ARPA Long-Range Tracking and Instrumentation Radar), a high-powered, ground-based radar system at the launch site, for signs of developing Sporadic-E layers. When conditions are right, Barjatya will give the launch command. A few minutes later, the rocket will be in flight.
The SEED science team and mission management team in front of the ARPA Long-Range Tracking and Instrumentation Radar (ALTAIR). The SEED team will use ALTAIR to monitor the ionosphere for signs of Sporadic-E layers and time the launch. U.S. Army Space and Missile Defense Command On ascent, the rocket will release colorful vapor tracers. Ground-based cameras will track the tracers to measure wind patterns in three dimensions. Once inside the Sporadic-E layer, the rocket will deploy four subpayloads — miniature detectors that will measure particle density and magnetic field strength at multiple points. The data will be transmitted back to the ground as the rocket descends.
On another night during the launch window, the team will launch a second, nearly identical rocket to collect additional data under potentially different conditions.
Barjatya and his team will use the data to improve computer models of the ionosphere, aiming to explain how Sporadic-E layers form so close to the equator.
“Sporadic-E layers are part of a much larger, more complicated physical system that is home to space-based assets we rely on every day,” Barjatya said. “This launch gets us closer to understanding another key piece of Earth’s interface to space.”
By Miles Hatfield
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Jun 12, 2025 Related Terms
Heliophysics Goddard Space Flight Center Heliophysics Division Ionosphere Missions NASA Centers & Facilities NASA Directorates Science & Research Science Mission Directorate Sounding Rockets Sounding Rockets Program The Solar System The Sun Uncategorized Wallops Flight Facility Weather and Atmospheric Dynamics Explore More
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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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