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Astrophysicist Gioia Rau Explores Cosmic ‘Time Machines’
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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 Hubble and Artificial Intelligence 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 Digs Up Galactic Time Capsule
This NASA/ESA Hubble Space Telescope image features the globular cluster NGC 1786. ESA/Hubble & NASA, M. Monelli; Acknowledgment: M. H. Özsaraç This NASA/ESA Hubble Space Telescope image features the field of stars that is NGC 1786. This globular cluster is located in the Large Magellanic Cloud (LMC), a small satellite galaxy of the Milky Way Galaxy that is approximately 160,000 light-years away from Earth. NGC 1786 itself is in the constellation Dorado. It was discovered in the year 1835 by Sir John Herschel.
The data for this image comes from an observing program that compares old globular clusters in nearby dwarf galaxies — the LMC, the Small Magellanic Cloud, and the Fornax dwarf spheroidal galaxy — to globular clusters in the Milky Way galaxy. Our galaxy contains over 150 of these old, spherical collections of tightly-bound stars, which astronomers have studied in depth — especially with Hubble images like this one, which show them in previously unattainable detail. Being very stable and long-lived, globular clusters act as galactic time capsules, preserving stars from the earliest stages of a galaxy’s formation.
Astronomers once thought that stars in a globular cluster all formed together at about the same time, but the study of old globular clusters in our galaxy uncovered multiple populations of stars with different ages. To use globular clusters as historical markers, we must understand how they form and where these stars of varying ages come from. This observing program examined old globular clusters like NGC 1786 in these external galaxies to see if they, too, contain multiple populations of stars. This research can tell us more about how the LMC originally formed, but also the Milky Way Galaxy, too.
Text Credit: ESA/Hubble
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Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
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Last Updated Jul 17, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
Astrophysics Astrophysics Division Globular Clusters Goddard Space Flight Center Hubble Space Telescope Star Clusters Stars 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 Star Clusters
Science Behind the Discoveries
Hubble’s Night Sky Challenge
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By NASA
This NASA Hubble Space Telescope image features a dense and dazzling array of blazing stars that form globular cluster ESO 591-12.NASA, ESA, and D. Massari (INAF — Osservatorio di Astrofisica e Scienza dello Spazio); Processing: Gladys Kober (NASA/Catholic University of America) A previously unexplored globular cluster glitters with multicolored stars in this NASA Hubble Space Telescope image. Globular clusters like this one, called ESO 591-12 or Palomar 8, are spherical collections of tens of thousands to millions of stars tightly bound together by gravity. Globular clusters generally form early in the galaxies’ histories in regions rich in gas and dust. Since the stars form from the same cloud of gas as it collapses, they typically hover around the same age. Strewn across this image of ESO 591-12 are a number of red and blue stars. The colors indicate their temperatures; red stars are cooler, while the blue stars are hotter.
Hubble captured the data used to create this image of ESO 591-12 as part of a study intended to resolve individual stars of the entire globular cluster system of the Milky Way. Hubble revolutionized the study of globular clusters since earthbound telescopes are unable to distinguish individual stars in the compact clusters. The study is part of the Hubble Missing Globular Clusters Survey, which targets 34 confirmed Milky Way globular clusters that Hubble has yet to observe.
The program aims to provide complete observations of ages and distances for all of the Milky Way’s globular clusters and investigate fundamental properties of still-unexplored clusters in the galactic bulge or halo. The observations will provide key information on the early stages of our galaxy, when globular clusters formed.
Image credit: NASA, ESA, and D. Massari (INAF — Osservatorio di Astrofisica e Scienza dello Spazio); Processing: Gladys Kober (NASA/Catholic University of America)
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By NASA
Scientists predict one of the major surveys by NASA’s upcoming Nancy Grace Roman Space Telescope may reveal around 100,000 celestial blasts, ranging from exploding stars to feeding black holes. Roman may even find evidence of some of the universe’s first stars, which are thought to completely self-destruct without leaving any remnant behind.
This simulation showcases the dynamic universe as NASA’s Nancy Grace Roman Space Telescope could see it over the course of its five-year primary mission. The video sparkles with synthetic supernovae from observations of the OpenUniverse simulated universe taken every five days (similar to the expected cadence of Roman’s High-Latitude Time-Domain Survey, which OpenUniverse simulates in its entirety). On top of the static sky of stars in the Milky Way and other galaxies, more than a million exploding stars flare into visibility and then slowly fade away. To highlight the dynamic physics happening and for visibility at this scale, the true brightness of each transient event has been magnified by a factor of 10,000 and no background light has been added to the simulated images. The video begins with Roman’s full field of view, which represents a single pointing of Roman’s camera, and then zooms into one square.Credit: NASA’s Goddard Space Flight Center and M. Troxel Cosmic explosions offer clues to some of the biggest mysteries of the universe. One is the nature of dark energy, the mysterious pressure thought to be accelerating the universe’s expansion.
“Whether you want to explore dark energy, dying stars, galactic powerhouses, or probably even entirely new things we’ve never seen before, this survey will be a gold mine,” said Benjamin Rose, an assistant professor at Baylor University in Waco, Texas, who led a study about the results. The paper is published in The Astrophysical Journal.
Called the High-Latitude Time-Domain Survey, this observation program will scan the same large region of the cosmos every five days for two years. Scientists will stitch these observations together to create movies that uncover all sorts of cosmic fireworks.
Chief among them are exploding stars. The survey is largely geared toward finding a special class of supernova called type Ia. These stellar cataclysms allow scientists to measure cosmic distances and trace the universe’s expansion because they peak at about the same intrinsic brightness. Figuring out how fast the universe has ballooned during different cosmic epochs offers clues to dark energy.
This landscape of “mountains” and “valleys” speckled with glittering stars is actually the edge of a nearby, young, star-forming region called NGC 3324 in the Carina Nebula. Captured in infrared light by NASA’s new James Webb Space Telescope, this image reveals for the first time previously invisible areas of star birth.Credit: NASA, ESA, CSA, and STScI In the new study, scientists simulated Roman’s entire High-Latitude Time-Domain Survey. The results suggest Roman could see around 27,000 type Ia supernovae—about 10 times more than all previous surveys combined.
Beyond dramatically increasing our total sample of these supernovae, Roman will push the boundaries of how far back in time we can see them. While most of those detected so far occurred within approximately the last 8 billion years, Roman is expected to see vast numbers of them earlier in the universe’s history, including more than a thousand that exploded more than 10 billion years ago and potentially dozens from as far back as 11.5 billion years. That means Roman will almost certainly set a new record for the farthest type Ia supernova while profoundly expanding our view of the early universe and filling in a critical gap in our understanding of how the cosmos has evolved over time.
“Filling these data gaps could also fill in gaps in our understanding of dark energy,” Rose said. “Evidence is mounting that dark energy has changed over time, and Roman will help us understand that change by exploring cosmic history in ways other telescopes can’t.”
But type Ia supernovae will be hidden among a much bigger sample of exploding stars Roman will see once it begins science operations in 2027. The team estimates Roman will also spot about 60,000 core-collapse supernovae, which occur when a massive star runs out of fuel and collapses under its own weight.
That’s different from type Ia supernovae, which originate from binary star systems that contain at least one white dwarf — the small, hot core remnant of a Sun-like star — siphoning material from a companion star. Core-collapse supernovae aren’t as useful for dark energy studies as type Ias are, but their signals look similar from halfway across the cosmos.
“By seeing the way an object’s light changes over time and splitting it into spectra — individual colors with patterns that reveal information about the object that emitted the light—we can distinguish between all the different types of flashes Roman will see,” said Rebekah Hounsell, an assistant research scientist at the University of Maryland-Baltimore County working at NASA’s Goddard Space Flight Center in Greenbelt, Maryland and a co-author of the study.
“With the dataset we’ve created, scientists can train machine-learning algorithms to distinguish between different types of objects and sift through Roman’s downpour of data to find them,” Hounsell added. “While searching for type Ia supernovae, Roman is going to collect a lot of cosmic ‘bycatch’—other phenomena that aren’t useful to some scientists, but will be invaluable to others.”
Hidden Gems
Thanks to Roman’s large, deep view of space, scientists say the survey should also unearth extremely rare and elusive phenomena, including even scarcer stellar explosions and disintegrating stars.
Upon close approach to a black hole, intense gravity can shred a star in a so-called tidal disruption event. The stellar crumbs heat up as they swirl around the black hole, creating a glow astronomers can see from across vast stretches of space-time. Scientists think Roman’s survey will unveil 40 tidal disruption events, offering a chance to learn more about black hole physics.
The team also estimates Roman will find about 90 superluminous supernovae, which can be 100 times brighter than a typical supernova. They pack a punch, but scientists aren’t completely sure why. Finding more of them will help astronomers weigh different theories.
Even rarer and more powerful, Roman could also detect several kilonovae. These blasts occur when two neutron stars — extremely dense cores leftover from stars that exploded as supernovae — collide. To date, there has been only one definitive kilonova detection. The team estimates Roman could spot five more.
NASA’s Roman Space Telescope will survey the same areas of the sky every few days following its launch in May 2027. Researchers will mine these data to identify kilonovae – explosions that happen when two neutron stars or a neutron star and a black hole collide and merge. When these collisions happen, a fraction of the resulting debris is ejected as jets, which move near the speed of light. The remaining debris produces hot, glowing, neutron-rich clouds that forge heavy elements, like gold and platinum. Roman’s extensive data will help astronomers better identify how often these events occur, how much energy they give off, and how near or far they are.Credit: NASA, ESA, J. Olmsted (STScI) That would help astronomers learn much more about these mysterious events, potentially including their fate. As of now, scientists are unsure whether kilonovae result in a single neutron star, a black hole, or something else entirely.
Roman may even spot the detonations of some of the first stars that formed in the universe. These nuclear furnaces were giants, up to hundreds of times more massive than our Sun, and unsullied by heavy elements that hadn’t yet formed.
They were so massive that scientists think they exploded differently than modern massive stars do. Instead of reaching the point where a heavy star today would collapse, intense gamma rays inside the first stars may have turned into matter-antimatter pairs (electrons and positrons). That would drain the pressure holding the stars up until they collapsed, self-destructing in explosions so powerful they’re thought to leave nothing behind.
So far, astronomers have found about half a dozen candidates of these “pair-instability” supernovae, but none have been confirmed.
“I think Roman will make the first confirmed detection of a pair-instability supernova,” Rose said — in fact the study suggests Roman will find more than 10. “They’re incredibly far away and very rare, so you need a telescope that can survey a lot of the sky at a deep exposure level in near-infrared light, and that’s Roman.”
A future rendition of the simulation could include even more types of cosmic flashes, such as variable stars and active galaxies. Other telescopes may follow up on the rare phenomena and objects Roman discovers to view them in different wavelengths of light to study them in more detail.
“Roman’s going to find a whole bunch of weird and wonderful things out in space, including some we haven’t even thought of yet,” Hounsell said. “We’re definitely expecting the unexpected.”
For more information about the Roman Space Telescope visit www.nasa.gov/roman.
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 Rochester, New York; and Teledyne Scientific & Imaging in Thousand Oaks, California.
By Ashley Balzer
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Jul 15, 2025 EditorAshley BalzerContactAshley Balzerashley.m.balzer@nasa.gov Related Terms
Nancy Grace Roman Space Telescope Astrophysics Black Holes Dark Energy Galaxies, Stars, & Black Holes Galaxies, Stars, & Black Holes Research Goddard Space Flight Center Science & Research Stars Supernovae The Universe Explore More
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By NASA
As Hubble marks three and a half decades of scientific breakthroughs and technical resilience, the “Hubble at 35 Years” symposium offers a platform to reflect on the mission’s historical, operational, and scientific legacy. Hubble’s trajectory—from early challenges to becoming a symbol of American scientific ingenuity—presents valuable lessons in innovation, collaboration, and crisis response. Bringing together scientists, engineers, and historians at NASA Headquarters ensures that this legacy informs current and future mission planning, including operations for the James Webb Space Telescope, Roman Space Telescope, and other next-generation observatories. The symposium not only honors Hubble’s transformative contributions but also reinforces NASA’s commitment to learning from the past to shape a more effective and ambitious future for space science.
Hubble at 35 Years
Lessons Learned in Scientific Discovery and NASA Flagship Mission Operations
October 16–17, 2025
James Webb Auditorium, NASA HQ, Washington, D.C.
The giant Hubble Space Telescope (HST) can be seen as it is suspended in space by Discovery’s Remote Manipulator System (RMS) following the deployment of part of its solar panels and antennae on April 25, 1990.NASA The story of the Hubble Space Telescope confirms its place as the most transformative and significant astronomical observatory in history. Once called “the eighth wonder of the world” by a former NASA administrator, Hubble’s development since its genesis in the early 1970s and its launch, repair, and ultimate impact since 1990 provide ample opportunity to apply insights from its legacy. Scientists and engineers associated with groundbreaking discoveries have always operated within contexts shaped by forces including the government, private industry, the military, and the public at large. The purpose of this symposium is to explore the insights from Hubble’s past and draw connections that can inform the development of mission work today and for the future.
Contact the Organizer Keep Exploring Discover More Topics From NASA
Hubble’s 35th Anniversary
Universe
Humans In Space
NASA History
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