Euclid: Relativistic effects in the dipole of the 2-point correlation function
Euclid: Relativistic effects in the dipole of the 2-point correlation function
Euclid preparation. Accurate and precise data-driven angular power spectrum covariances
Euclid preparation. Accurate and precise data-driven angular power spectrum covariances
Major telescope hosts world's largest digital camera: how it will transform astronomy
Nature, Published online: 11 June 2025; doi:10.1038/d41586-025-01798-2
Massive telescope will map the Universe and provide an evolving record of the Solar System and distant stars.Molecular hydrogen in the extremely metal- and dust-poor galaxy Leo P
Nature, Published online: 11 June 2025; doi:10.1038/s41586-025-09115-7
Observations from the JWST MIRI-MRS instrument reveal the detection of rotational emission from molecular hydrogen near the only O-type star in the 3% solar metallicity galaxy Leo P, providing confirmation that significant quantities of molecular gas can form in such metal- and dust-poor environments.NASA’s Webb ‘UNCOVERs’ Galaxy Population Driving Cosmic Renovation
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NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025
Astronomers using data from NASA’s James Webb Space Telescope have identified dozens of small galaxies that played a starring role in a cosmic makeover that transformed the early universe into the one we know today.
“When it comes to producing ultraviolet light, these small galaxies punch well above their weight,” said Isak Wold, an assistant research scientist at Catholic University of America in Washington and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “Our analysis of these tiny but mighty galaxies is 10 times more sensitive than previous studies, and shows they existed in sufficient numbers and packed enough ultraviolet power to drive this cosmic renovation.”
Wold discussed his findings Wednesday at the 246th meeting of the American Astronomical Society in Anchorage, Alaska. The study took advantage of existing imaging collected by Webb’s NIRCam (Near-Infrared Camera) instrument, as well as new observations made with its NIRSpec (Near-Infrared Spectrograph) instrument.
Image A: Webb search finds dozens of tiny, young star-forming galaxies Symbols mark the locations of young, low-mass galaxies bursting with new stars when the universe was about 800 million years old. Using a filter sensitive to such galaxies, NASA’s James Webb Space Telescope imaged them with the help of a natural gravitational lens created by the massive galaxy cluster Abell 2744. In all, 83 young galaxies were found, but only the 20 shown here (white diamonds) were selected for deeper study. The inset zooms into one of the galaxies.
Download high-resolution images from NASA’s Scientific Visualization Studio NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025
The tiny galaxies were discovered by Wold and his Goddard colleagues, Sangeeta Malhotra and James Rhoads, by sifting through Webb images captured as part of the UNCOVER (Ultradeep NIRSpec and NIRCam ObserVations before the Epoch of Reionization) observing program, led by Rachel Bezanson at the University of Pittsburgh in Pennsylvania.
The project mapped a giant galaxy cluster known as Abell 2744, nicknamed Pandora’s cluster, located about 4 billion light-years away in the southern constellation Sculptor. The cluster’s mass forms a gravitational lens that magnifies distant sources, adding to Webb’s already considerable reach.
Image B: Galaxy cluster helps reveal young, low-mass galaxies bursting with stars White diamonds show the locations of 20 of the 83 young, low-mass, starburst galaxies found in infrared images of the giant galaxy cluster Abell 2744. This composite incorporates images taken through three NIRCam filters (F200W as blue, F410M as green, and F444W as red). The F410M filter is highly sensitive to light emitted by doubly ionized oxygen — oxygen atoms that have been stripped of two electrons — at a time when reionization was well underway. Emitted as green light, the glow was stretched into the infrared as it traversed the expanding universe over billions of years. The cluster’s mass acts as a natural magnifying glass, allowing astronomers to see these tiny galaxies as they were when the universe was about 800 million years old. NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025
For much of its first billion years, the universe was immersed in a fog of neutral hydrogen gas. Today, this gas is ionized — stripped of its electrons. Astronomers, who refer to this transformation as reionization, have long wondered which types of objects were most responsible: big galaxies, small galaxies, or supermassive black holes in active galaxies. As one of its main goals, NASA’s Webb was specifically designed to address key questions about this major transition in the history of the universe.
Recent studies have shown that small galaxies undergoing vigorous star formation could have played an outsized role. Such galaxies are rare today, making up only about 1% of those around us. But they were abundant when the universe was about 800 million years old, an epoch astronomers refer to as redshift 7, when reionization was well underway.
The team searched for small galaxies of the right cosmic age that showed signs of extreme star formation, called starbursts, in NIRCam images of the cluster.
“Low-mass galaxies gather less neutral hydrogen gas around them, which makes it easier for ionizing ultraviolet light to escape,” Rhoads said. “Likewise, starburst episodes not only produce plentiful ultraviolet light — they also carve channels into a galaxy’s interstellar matter that helps this light break out.”
Image C: A deeper look into small, young, star-forming galaxies during reionization At left is an enlarged infrared view of galaxy cluster Abell 2744 with three young, star-forming galaxies highlighted by green diamonds. The center column shows close-ups of each galaxy, along with their designations, the amount of magnification provided by the cluster’s gravitational lens, their redshifts (shown as z — all correspond to a cosmic age of about 790 million years), and their estimated mass of stars. At right, measurements from NASA’s James Webb Space Telescope’s NIRSpec instrument confirm that the galaxies produce strong emission in the light of doubly ionized oxygen (green bars), indicating vigorous star formation is taking place. NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025
The astronomers looked for strong sources of a specific wavelength of light that signifies the presence of high-energy processes: a green line emitted by oxygen atoms that have lost two electrons. Originally emitted as visible light in the early cosmos, the green glow from doubly ionized oxygen was stretched into the infrared as it traversed the expanding universe and eventually reached Webb’s instruments.
This technique revealed 83 small starburst galaxies as they appear when the universe was 800 million years old, or about 6% of its current age of 13.8 billion years. The team selected 20 of these for deeper inspection using NIRSpec.
“These galaxies are so small that, to build the equivalent stellar mass of our own Milky Way galaxy, you’d need from 2,000 to 200,000 of them,” Malhotra said. “But we are able to detect them because of our novel sample selection technique combined with gravitational lensing.”
Image D: Tiny but mighty galaxy helped clear cosmic fog One of the most interesting galaxies of the study, dubbed 41028 (the green oval at center), has an estimated stellar mass of just 2 million Suns — comparable to the masses of the largest star clusters in our own Milky Way galaxy. NASA/ESA/CSA/Bezanson et al. 2024 and Wold et al. 2025
Similar types of galaxies in the present-day universe, such as green peas, release about 25% of their ionizing ultraviolet light into surrounding space. If the low-mass starburst galaxies explored by Wold and his team release a similar amount, they can account for all of the ultraviolet light needed to convert the universe’s neutral hydrogen to its ionized form.
The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and CSA (Canadian Space Agency).
To learn more about Webb, visit:
By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Click any image above to open a larger version.
Download high-resolution images from NASA’s Scientific Visualization Studio.
Media ContactsLaura Betz – laura.e.betz@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Article: Types of Galaxies
Video: Different types of galaxies
Related For Kids En Español Keep Exploring Related Topics James Webb Space TelescopeShare Details Last Updated Jun 11, 2025 Editor Marty McCoy Contact Laura Betz laura.e.betz@nasa.gov Related Terms
NASA+ Documentary “Cosmic Dawn” Reveals Untold Story of James Webb Space Telescope
What does it take to gaze through time to our universe’s very first stars and galaxies?
NASA answers this question in its new documentary, “Cosmic Dawn: The Untold Story of the James Webb Space Telescope.” The agency’s original documentary, which chronicles the story of the most powerful telescope ever deployed in space, was released Wednesday, June 11.
Cosmic Dawn offers an unprecedented glimpse into the delicate assembly, rigorous testing, and triumphant launch of NASA’s James Webb Space Telescope. The documentary showcases the complexity involved in creating a telescope capable of peering billions of years into the past.
Cosmic Dawn is now available for streaming on NASA’s YouTube, NASA+, and select local theaters. The trailer is available on NASA+ and YouTube.
Relive the pitfalls and the triumphs of the world’s most powerful space telescope—from developing the idea of an impossible machine to watching with bated breath as it unfolded, hurtling through space a million miles away from Earth. Watch the Documentary on YouTubeThe film features never-before-seen footage captured by the Webb film crew, offering intimate access to the challenges and triumphs faced by the team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland — the birthplace of Webb.
“At NASA, we’re thrilled to share the untold story of our James Webb Space Telescope in our new film ‘Cosmic Dawn,’ celebrating not just the discoveries, but the extraordinary people who made it all happen, for the benefit of humanity,” said Rebecca Sirmons, head of NASA+ at the agency’s headquarters in Washington.
From its vantage point more than a million miles from Earth and a massive sunshield to block the light of our star, Webb’s First Deep Field the deepest and sharpest infrared images of the universe that the world had seen.
Webb’s images have dazzled people around the globe, capturing the very faint light of the first stars and galaxies that formed more than 13.5 billion years ago. These are baby pictures from an ancient past when the first objects were turning on and emitting light after the Big Bang. Webb has also given us new insights into black holes, planets both inside and outside of our own solar system, and many other cosmic phenomena.
Webb was a mission that was going to be spectacular whether that was good or bad — if it failed or was successful. It was always going to make historySophia roberts
NASA Video Producer
NASA’s biggest and most powerful space telescope was also its most technically complicated to build. It was harder still to deploy, with more than 300 critical components that had to deploy perfectly. The risks were high in this complicated dance of engineering, but the rewards were so much higher.
“Webb was a mission that was going to be spectacular whether that was good or bad — if it failed or was successful,” said video producer Sophia Roberts, who chronicled the five years preceding Webb’s launch. “It was always going to make history.”
NASA scientists like Nobel Laureate Dr. John Mather conceived Webb to look farther and deeper into origins of our universe using cutting edge infrared technology and massive mirrors to collect incredibly rich information about our universe, from the light of the first galaxies to detailed images of planets in our own solar system.
To achieve this goal, NASA and its partners faced unprecedented hurdles.
Webb’s development introduced questions that no one had asked before. How do you fit a telescope with the footprint of a tennis court into a rocket? How do you clean 18 sensitive mirrors when a single scratch could render them inoperable? How do you maintain critical testing while hurricane stormwater pours through ceilings?
A technician inspects the James Webb Space Telescope primary mirrors at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.NASA/Sophia Roberts
Cosmic Dawn captures 25 years of formidable design constraints, high-stake assessments, devastating natural disasters, a global pandemic and determined individuals who would let none of that get in the way of getting this monumental observatory to its rightful place in the cosmos.
“There was nothing easy about Webb at all,” said Webb project manager Bill Ochs. “I don’t care what aspect of the mission you looked at.”
Viewers will experience a one-of-a-kind journey as NASA and its partners tackle these dilemmas — and more — through ingenuity, teamwork, and unbreakable determination.
“The inspiration of trying to discover something — to build something that’s never been built before, to discover something that’s never been known before — it keeps us going,” Mather said. “We are pleased and privileged in our position here at NASA to be able to carry out this [purpose] on behalf of the country and the world.”
Bound by NASA’s 66-year commitment to document and share its work with the public, Cosmic Dawn details every step toward Webb’s launch and science results.
Learn more at nasa.gov/cosmicdawnBy Laine Havens,
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Katie Konans,
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Spacecraft films first view of the Sun's south pole
'Impossible' particle that hit Earth may have been dark matter
These images are the first time we have seen the sun's south pole
Tue 17 Jun 13:00: Exoplanet Demographics: A Journey Through Space and Time
Exoplanet demographic surveys provide a unique window into planet formation and evolution. In this talk, I will showcase three distinct features in the exoplanet population and offer theoretical interpretation of the physical mechanisms that sculpt them. I will first highlight what recent measurements extending the exoplanetary census beyond the solar neighborhood can tell us about how planet formation has evolved over cosmic time. Second, I will explore the origins of “desert dweller” planets that reside deep in the “sub-Jovian desert” (2 < Rp < 10 R_Earth, periods < 3 days), a region sparsely populated but no longer empty thanks to recent surveys. I will show that “desert dwellers” may serve as laboratories to study the fate of hot Jupiters and the interiors of giant planets in exquisite detail. Lastly, I will discuss the role atmospheric photoevaporation plays in carving the orbital period distribution of puffy, gas-rich sub-Saturns; in this picture, the sub-Saturn orbital period distribution can be leveraged to estimate a fundamental property of the planet population – the core mass function of gas-rich planets. I will outline the observational implications of our theoretical work throughout the talk.
- Speaker: Timothy Hallatt (MIT)
- Tuesday 17 June 2025, 13:00-14:00
- Venue: Ryle seminar room + ONLINE - Details to be sent by email.
- Series: Exoplanet Seminars; organiser: Dr Dolev Bashi.
Euclid preparation: The NISP spectroscopy channel, on ground performance and calibration
Euclid preparation: The NISP spectroscopy channel, on ground performance and calibration
Fri 13 Jun 13:00: Constraining Inflation with Numerical Relativity
Cosmic inflation is the leading paradigm for describing the early universe, addressing fundamental issues such as the horizon and flatness problems. However, a key unresolved question is the nature of its initial conditions. In this talk, I will discuss how numerical relativity helps studying inflationary spacetimes with inhomogeneous initial conditions, particularly in the presence of strong gravitational effects from large inhomogeneities. Numerical simulations allow us to map out the phase space of initial conditions that lead to sufficient duration of slow roll inflation versus those that do not. The results strongly depend on the inflationary model, with a rule of thumb that the models with near- or super-Planckian characteristic scales are more robust to matter and geometric inhomogeneities than those with sub-Planckian scales. We mainly focus on the study of α-attractor models and our simulation results allow us to find a lower bound on the tensor-to-scalar ratio r.
- Speaker: Panos Giannadakis, Queen Mary University of London
- Friday 13 June 2025, 13:00-14:00
- Venue: Potter room/Zoom.
- Series: DAMTP Friday GR Seminar; organiser: Xi Tong.
NASA’s CODEX Captures Unique Views of Sun’s Outer Atmosphere
- NASA’s CODEX investigation captured images of the Sun’s outer atmosphere, the corona, showcasing new aspects of its gusty, uneven flow.
- The CODEX instrument, located on the International Space Station, is a coronagraph — a scientific tool that creates an artificial eclipse with physical disks — that measures the speed and temperature of solar wind using special filters.
- These first-of-their-kind measurements will help scientists improve models of space weather and better understand the Sun’s impact on Earth.
Scientists analyzing data from NASA’s CODEX (Coronal Diagnostic Experiment) investigation have successfully evaluated the instrument’s first images, revealing the speed and temperature of material flowing out from the Sun. These images, shared at a press event Tuesday at the American Astronomical Society meeting in Anchorage, Alaska, illustrate the Sun’s outer atmosphere, or corona, is not a homogenous, steady flow of material, but an area with sputtering gusts of hot plasma. These images will help scientists improve their understanding of how the Sun impacts Earth and our technology in space.
“We really never had the ability to do this kind of science before,” said Jeffrey Newmark, a heliophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and the principal investigator for CODEX. “The right kind of filters, the right size instrumentation — all the right things fell into place. These are brand new observations that have never been seen before, and we think there’s a lot of really interesting science to be done with it.”
The Sun continuously radiates material in the form of the solar wind. The Sun’s magnetic field shapes this material, sometimes creating flowing, ray-like formations called coronal streamers. In this view from NASA’s CODEX instrument, large dark spots block much of the bright light from the Sun. Blocking this light allows the instrument’s sensitive equipment to capture the faint light of the Sun’s outer atmosphere. NASA/KASI/INAF/CODEX
NASA’s CODEX is a solar coronagraph, an instrument often employed to study the Sun’s faint corona, or outer atmosphere, by blocking the bright face of the Sun. The instrument, which is installed on the International Space Station, creates artificial eclipses using a series of circular pieces of material called occulting disks at the end of a long telescope-like tube. The occulting disks are about the size of a tennis ball and are held in place by three metal arms.
Scientists often use coronagraphs to study visible light from the corona, revealing dynamic features, such as solar storms, that shape the weather in space, potentially impacting Earth and beyond.
NASA missions use coronagraphs to study the Sun in various ways, but that doesn’t mean they all see the same thing. Coronagraphs on the joint NASA-ESA Solar and Heliospheric Observatory (SOHO) mission look at visible light from the solar corona with both a wide field of view and a smaller one. The CODEX instrument’s field of view is somewhere in the middle, but looks at blue light to understand temperature and speed variations in the background solar wind.
In this composite image of overlapping solar observations, the center and left panels show the field-of-view coverage of the different coronagraphs with overlays and are labeled with observation ranges in solar radii. The third panel shows a zoomed-in, color-coded portion of the larger CODEX image. It highlights the temperature ratios in that portion of the solar corona using CODEX 405.0 and 393.5 nm filters. NASA/ESA/SOHO/KASI/INAF/CODEX
“The CODEX instrument is doing something new,” said Newmark. “Previous coronagraph experiments have measured the density of material in the corona, but CODEX is measuring the temperature and speed of material in the slowly varying solar wind flowing out from the Sun.”
These new measurements allow scientists to better characterize the energy at the source of the solar wind.
The CODEX instrument uses four narrow-band filters — two for temperature and two for speed — to capture solar wind data. “By comparing the brightness of the images in each of these filters, we can tell the temperature and speed of the coronal solar wind,” said Newmark.
Understanding the speed and temperature of the solar wind helps scientists build a more accurate picture of the Sun, which is necessary for modeling and predicting the Sun’s behaviors.
“The CODEX instrument will impact space weather modeling by providing constraints for modelers to use in the future,” said Newmark. “We’re excited for what’s to come.”
by NASA Science Editorial Team
NASA’s Goddard Space Flight Center, Greenbelt, Md
CODEX is a collaboration between NASA Goddard Space Flight Center and the Korea Astronomy and Space Science Institute (KASI) with additional contribution from Italy’s National Institute for Astrophysics (INAF).
Share Details Last Updated Jun 10, 2025 Related TermsSilicate clouds and a circumplanetary disk in the YSES-1 exoplanet system
Nature, Published online: 10 June 2025; doi:10.1038/s41586-025-09174-w
Silicate clouds and a circumplanetary disk in the YSES-1 exoplanet systemMon 16 Jun 13:00: A short history of KiDS cosmic shear measurements - a.k.a. Euclid from the ground
In this seminar, I will give a historical overview of the cosmic shear measurements conducted with the Kilo-Degree Survey (KiDS) and their cosmological implications. I will focus on the progress in methodology and systematic error control that has been achieved over the past decade, with a particular focus on the observational problems that were solved to greatly increase the robustness of these analyses. I will present the final KiDS-Legacy results and highlight the lessons learned from KiDS that are most relevant for Euclid.
- Speaker: Hendrik Hildebrandt (Ruhr University Bochum)
- Monday 16 June 2025, 13:00-14:00
- Venue: CMS, Pav. B, CTC Common Room (B1.19) [Potter Room].
- Series: Cosmology Lunch; organiser: Louis Legrand.