From The National Science Foundation NOIRLab (National Optical-Infrared Astronomy Research Laboratory) The University of Arizona and The Space Science Telescope Institute via EarthSky: “Background glow of the universe is oddly bright”

From The National Science Foundation NOIRLab (National Optical-Infrared Astronomy Research Laboratory)


The University of Arizona


The Space Science Telescope Institute




April 3, 2022
Paul Scott Anderson

Astronomers say the universe’s background glow is twice as bright as previously thought. NASA’s New Horizons spacecraft discovered the unexpected anomaly when it observed a dark region in space with few stars and galaxies. Image via NASA/ Joseph Olmsted/ STSCI/ ScienceNews.

We might think of space as an unending void of pitch black darkness, punctuated only by tiny lights of stars and distant galaxies. But is it really that dark? Not quite! There’s a small but significant amount of background light that permeates the visible universe. It’s the faint glow that emanates from stars, galaxies, dust and gas. Astronomers said on March 3, 2022, that they’ve found this glow to be about twice as bright as expected.

About half the amount of background light – called the cosmic optical background (COB) – can be accounted for by the usual stars and galaxies. But the other half is a bit mysterious. Where does this extra light come from? Astronomers used data from NASA’s New Horizons spacecraft, which conducted its historic flyby of Pluto in 2015.

The researchers published their peer-reviewed findings in The Astrophysical Journal Letters on March 3, 2022. Liz Kruesi wrote about the intriguing new results for ScienceNews on March 22, 2022.

The universe is a dark place, a seemingly unending expanse of blackness. Only the light of stars, dust and galaxies provide any illumination, as in this illustration of our Milky Way galaxy. Scientists said, in March 2022, that the background glow – called the cosmic optical background, or COB – is actually about twice as bright as previously thought. Image via The American Museum of Natural History /

The universe’s background glow as seen by New Horizons

The background glow in the universe is difficult to see, but detectable. Most of it, as seen from our earthly vantage point, is washed out by the brighter light of the sun reflecting off dust in the inner solar system. This is known as the zodiacal light when seen from Earth. So what is the best way to see the faint cosmic glow? From a location much farther out in the solar system!

The researchers used images from the New Horizons spacecraft, which is way, way out in the outer fringes of the solar system, well past Pluto. Using its LORRI (Long Range Reconnaissance Imager) camera, New Horizons took images of a spot in the background universe that contained few if any stars or galaxies. About as dark a patch of sky as you can get.

The researchers digitally removed other sources of light from the images, such as stars and galaxies. They also removed extraneous light generated by the spacecraft’s nuclear power source. By doing all this, the researchers could then determine how much COB (cosmic optical background) there really was and measure its brightness.

Anomaly reveals a cosmic mystery

The astronomers expected that these new measurements would pretty much match those previously taken from Earth over the years. But, surprisingly, they didn’t. In fact, the background light was twice as bright as expected. As lead author Tod Lauer, an astronomer at the National Science Foundation’s NOIRLab in Tucson, Arizona, told ScienceNews:

“It turns out that the galaxies that we know about can account for about half of the level we see.”

ScienceNews also quoted co-author Marc Postman of the Space Telescope Science Institute (STScI), saying:

“There’s clearly an anomaly. Now we need to try to understand it and explain it.”

The zodiacal light (the diffuse upward-pointing glow in this image) is the faint reflection of sunlight off dust grains in the inner solar system. Albeit beautiful, light such as this interferes with astronomers’ ability to measure the even fainter background glow of the universe. Christoph Stopka in Westcliffe, Colorado, took this gorgeous image of the zodiacal light on March 1, 2022, over the high peaks of the Sangre de Cristo mountain range, part of the Colorado Rockies. Thank you, Cristoph!

In other words, only half of the background light observed can be explained by light from known galaxies and stars. How is that possible?

Possible explanations for the background glow

Why are the new measurements so different from past ones? Of course, they are more sensitive and accurate than is possible with Earth-based measurements. But, twice as much COB is still a big discrepancy from earlier studies.

One possibility is that the extra light may be coming from rogue, nomad stars floating around in intergalactic space. Like rogue planets, they drift freely, not trapped in any galaxies. Could there be enough of them to account for the extra background light?

Or, perhaps there are compact galaxies that are too faint for even the Hubble Space Telescope to detect. If such galaxies exist, they may potentially be found by the James Webb Space Telescope. Webb will start observing this summer, and is expected to provide images that will surpass those from Hubble.

A very subtle beast

Another possibility is that the researchers overlooked something in the analysis itself. For example, could there still be some extraneous light from the spacecraft itself? What about the light from our home galaxy, the Milky Way? Astrophysicist Michael Zemcov of The Rochester Institute of Technology in New York surmised in ScienceNews that the reflected light from the Milky Way’s dust is:

“… a very subtle beast, and our uncertainties likely get dominated by it at some point, just because it’s not very well understood.”

The results are certainly intriguing, but more work is needed to figure them out.

Zemcov continued, saying:

“I’m glad it got done; it’s absolutely a necessary measurement. I think there’s a conversation there about details … and our uncertainties likely get dominated by it at some point, just because it’s not very well understood. There is something going on that we weren’t expecting, which is where the fun part of science kicks in.”

Future studies

In addition to the LORRI images from New Horizons, there are other upcoming missions and projects that may shed more light on the mystery, as it were. These include the CIBER-2 experiment and SPHEREx. Also, researchers will continue to analyze older LORRI images, as well as take new LORRI images of other regions of the sky not imaged before.

CIBER final flight on the Black Brant XII rocket. Photo courtesy of the NASA Wallops Flight Facility.

See the full article here.

See also the full Science News article here .


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As of 2019, the The University of Arizona enrolled 45,918 students in 19 separate colleges/schools, including The University of Arizona College of Medicine in Tucson and Phoenix and the James E. Rogers College of Law, and is affiliated with two academic medical centers (Banner – University Medical Center Tucson and Banner – University Medical Center Phoenix). The University of Arizona is one of three universities governed by the Arizona Board of Regents. The university is part of the Association of American Universities and is the only member from Arizona, and also part of the Universities Research Association . The university is classified among “R1: Doctoral Universities – Very High Research Activity”.

Known as the Arizona Wildcats (often shortened to “Cats”), The University of Arizona’s intercollegiate athletic teams are members of the Pac-12 Conference of the NCAA. The University of Arizona athletes have won national titles in several sports, most notably men’s basketball, baseball, and softball. The official colors of the university and its athletic teams are cardinal red and navy blue.

After the passage of the Morrill Land-Grant Act of 1862, the push for a university in Arizona grew. The Arizona Territory’s “Thieving Thirteenth” Legislature approved The University of Arizona in 1885 and selected the city of Tucson to receive the appropriation to build the university. Tucson hoped to receive the appropriation for the territory’s mental hospital, which carried a $100,000 allocation instead of the $25,000 allotted to the territory’s only university Arizona State University was also chartered in 1885, but it was created as Arizona’s normal school, and not a university). Flooding on the Salt River delayed Tucson’s legislators, and by the time they reached Prescott, back-room deals allocating the most desirable territorial institutions had been made. Tucson was largely disappointed with receiving what was viewed as an inferior prize.

With no parties willing to provide land for the new institution, the citizens of Tucson prepared to return the money to the Territorial Legislature until two gamblers and a saloon keeper decided to donate the land to build the school. Construction of Old Main, the first building on campus, began on October 27, 1887, and classes met for the first time in 1891 with 32 students in Old Main, which is still in use today. Because there were no high schools in Arizona Territory, the university maintained separate preparatory classes for the first 23 years of operation.


The University of Arizona is classified among “R1: Doctoral Universities – Very high research activity”. UArizona is the fourth most awarded public university by National Aeronautics and Space Administration for research. The University of Arizona was awarded over $325 million for its Lunar and Planetary Laboratory (LPL) to lead NASA’s 2007–08 mission to Mars to explore the Martian Arctic, and $800 million for its OSIRIS-REx mission, the first in U.S. history to sample an asteroid.

National Aeronautics Space Agency OSIRIS-REx Spacecraft.

The LPL’s work in the Cassini spacecraft orbit around Saturn is larger than any other university globally.

National Aeronautics and Space Administration/European Space Agency [La Agencia Espacial Europea][Agence spatiale européenne][Europäische Weltraumorganisation](EU)/ASI Italian Space Agency [Agenzia Spaziale Italiana](IT) Cassini Spacecraft.

The University of Arizona laboratory designed and operated the atmospheric radiation investigations and imaging on the probe. The University of Arizona operates the HiRISE camera, a part of the Mars Reconnaissance Orbiter.

U Arizona NASA Mars Reconnaisance HiRISE Camera.

NASA Mars Reconnaissance Orbiter.

While using the HiRISE camera in 2011, University of Arizona alumnus Lujendra Ojha and his team discovered proof of liquid water on the surface of Mars—a discovery confirmed by NASA in 2015. The University of Arizona receives more NASA grants annually than the next nine top NASA/JPL-Caltech-funded universities combined. As of March 2016, The University of Arizona’s Lunar and Planetary Laboratory is actively involved in ten spacecraft missions: Cassini VIMS; Grail; the HiRISE camera orbiting Mars; the Juno mission orbiting Jupiter; Lunar Reconnaissance Orbiter (LRO); Maven, which will explore Mars’ upper atmosphere and interactions with the sun; Solar Probe Plus, a historic mission into the Sun’s atmosphere for the first time; Rosetta’s VIRTIS; WISE; and OSIRIS-REx, the first U.S. sample-return mission to a near-earth asteroid, which launched on September 8, 2016.

NASA – GRAIL Flying in Formation (Artist’s Concept). Credit: NASA.
National Aeronautics Space Agency Juno at Jupiter.

NASA/Lunar Reconnaissance Orbiter.


NASA Parker Solar Probe Plus named to honor Pioneering Physicist Eugene Parker. The Johns Hopkins University Applied Physics Lab.

National Aeronautics and Space Administration Wise/NEOWISE Telescope.

The University of Arizona students have been selected as Truman, Rhodes, Goldwater, and Fulbright Scholars. According to The Chronicle of Higher Education, UArizona is among the top 25 producers of Fulbright awards in the U.S.

The University of Arizona is a member of the Association of Universities for Research in Astronomy , a consortium of institutions pursuing research in astronomy. The association operates observatories and telescopes, notably Kitt Peak National Observatory just outside Tucson.

National Science Foundation NOIRLab National Optical Astronomy Observatory Kitt Peak National Observatory on Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers (55 mi) west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft). annotated.

Led by Roger Angel, researchers in the Steward Observatory Mirror Lab at The University of Arizona are working in concert to build the world’s most advanced telescope. Known as the Giant Magellan Telescope (CL), it will produce images 10 times sharper than those from the Earth-orbiting Hubble Telescope.

GMT Giant Magellan Telescope(CL) 21 meters, to be at the Carnegie Institution for Science’s NOIRLab NOAO Las Campanas Observatory(CL), some 115 km (71 mi) north-northeast of La Serena, Chile, over 2,500 m (8,200 ft) high.

The telescope is set to be completed in 2021. GMT will ultimately cost $1 billion. Researchers from at least nine institutions are working to secure the funding for the project. The telescope will include seven 18-ton mirrors capable of providing clear images of volcanoes and riverbeds on Mars and mountains on the moon at a rate 40 times faster than the world’s current large telescopes. The mirrors of the Giant Magellan Telescope will be built at The University of Arizona and transported to a permanent mountaintop site in the Chilean Andes where the telescope will be constructed.

Reaching Mars in March 2006, the Mars Reconnaissance Orbiter contained the HiRISE camera, with Principal Investigator Alfred McEwen as the lead on the project. This National Aeronautics and Space Agency mission to Mars carrying the UArizona-designed camera is capturing the highest-resolution images of the planet ever seen. The journey of the orbiter was 300 million miles. In August 2007, The University of Arizona, under the charge of Scientist Peter Smith, led the Phoenix Mars Mission, the first mission completely controlled by a university. Reaching the planet’s surface in May 2008, the mission’s purpose was to improve knowledge of the Martian Arctic. The Arizona Radio Observatory , a part of The University of Arizona Department of Astronomy Steward Observatory , operates the Submillimeter Telescope on Mount Graham.

University of Arizona Radio Observatory at NOAO Kitt Peak National Observatory, AZ USA, U Arizona Department of Astronomy and Steward Observatory at altitude 2,096 m (6,877 ft).

The National Science Foundation funded the iPlant Collaborative in 2008 with a $50 million grant. In 2013, iPlant Collaborative received a $50 million renewal grant. Rebranded in late 2015 as “CyVerse”, the collaborative cloud-based data management platform is moving beyond life sciences to provide cloud-computing access across all scientific disciplines.

In June 2011, the university announced it would assume full ownership of the Biosphere 2 scientific research facility in Oracle, Arizona, north of Tucson, effective July 1. Biosphere 2 was constructed by private developers (funded mainly by Texas businessman and philanthropist Ed Bass) with its first closed system experiment commencing in 1991. The university had been the official management partner of the facility for research purposes since 2007.

U Arizona mirror lab-Where else in the world can you find an astronomical observatory mirror lab under a football stadium?

University of Arizona’s Biosphere 2, located in the Sonoran desert. An entire ecosystem under a glass dome? Visit our campus, just once, and you’ll quickly understand why The University of Arizona is a university unlike any other.

University of Arizona Landscape Evolution Observatory at Biosphere 2.

We are the Space Telescope Science Institute in Baltimore, Maryland, operated by the Association of Universities for Research in Astronomy. We help humanity explore the universe with advanced space telescopes and ever-growing data archives.

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Founded in 1982, we have helped guide the most famous observatory in history, the Hubble Space Telescope.

National Aeronautics and Space Administration(US)/The European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU) Hubble Space Telescope.

Since its launch in 1990, we have performed the science operations for Hubble. We also lead the science and mission operations for the James Webb Space Telescope (JWST), scheduled for launch in 2019.

National Aeronautics Space Agency(US)/European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU)/ Canadian Space Agency [Agence Spatiale Canadienne](CA) James Webb Infrared Space Telescope(US) annotated, finally launched December 25, 2021, ten years late.

We will perform parts of the science operations for the Nancy Grace Roman Space Telescope, in formulation for launch in the mid-2020s, and we are partners on several other NASA missions.

National Aeronautics and Space Administration Nancy Grace Roman Space Telescope [WFIRST] depiction.

Our staff conducts world-class scientific research; our Barbara A. Mikulski Archive for Space Telescopes (MAST) curates and disseminates data from over 20 astronomical missions; we bring science to the world through internationally recognized news, education, and public outreach programs. We value our diverse workforce and civility in the workplace, and seek to be an example for others to follow.

What is NOIRLab?

NSF’s NOIRLab (National Optical-Infrared Astronomy Research Laboratory) , the US center for ground-based optical-infrared astronomy, operates the international Gemini Observatory (a facility of National Science Foundation , NRC–Canada, ANID–Chile, MCTIC–Brazil, MINCyT–Argentina, and Korea Astronomy and Space Science Institute [한국천문연구원] (KR)), NOAO Kitt Peak National Observatory (KPNO), Cerro Tololo Inter-American Observatory(CL) (CTIO), the Community Science and Data Center (CSDC), and Vera C. Rubin Observatory (in cooperation with DOE’s SLAC National Accelerator Laboratory). It is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with NSF and is headquartered in Tucson, Arizona. The astronomical community is honored to have the opportunity to conduct astronomical research on Iolkam Du’ag (Kitt Peak) in Arizona, on Maunakea in Hawaiʻi, and on Cerro Tololo and Cerro Pachón in Chile. We recognize and acknowledge the very significant cultural role and reverence that these sites have to the Tohono O’odham Nation, to the Native Hawaiian community, and to the local communities in Chile, respectively.

National Science Foundation NOIRLab’s Gemini North Frederick C Gillett telescope at Mauna Kea Observatory Hawai’i Altitude 4,213 m (13,822 ft).

The National Science Foundation NOIRLab National Optical Astronomy Observatory Gemini South telescope on the summit of Cerro Pachón at an altitude of 7200 feet. There are currently two telescopes commissioned on Cerro Pachón, Gemini South and the SOAR Telescope — Southern Astrophysics Research Telescope. A third, the Vera C. Rubin Observatory, is under construction.

The National Science Foundation NOIRLab National Optical Astronomy Observatory Vera C. Rubin Observatory [LSST] Telescope currently under construction on the El Peñón peak at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing NSF NOIRLab NOAO The Association of Universities for Research in Astronomy (AURA) Gemini South Telescope and Southern Astrophysical Research Telescope.

Carnegie Institution for Science’s Las Campanas Observatory on Cerro Pachón in the southern Atacama Desert of Chile in the Atacama Region approximately 100 kilometres (62 mi) northeast of the city of La Serena,near the southern end and over 2,500 m (8,200 ft) high.

National Science Foundation NOIRLab National Optical Astronomy Observatory Kitt Peak National Observatory on Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers (55 mi) west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft). annotated.

NSF NOIRLab NOAO Cerro Tololo Inter-American Observatory(CL) approximately 80 km to the East of La Serena, Chile, at an altitude of 2200 meters.

The NOAO-Community Science and Data Center

This work is supported in part by The Department of Energy Office of Science. The Dark Energy Survey is a collaboration of more than 400 scientists from 26 institutions in seven countries. Funding for the DES Projects has been provided by the US Department of Energy Office of Science, The National Science Foundation, Ministry of Science and Education of Spain, The Science and Technology Facilities Council (UK), The Higher Education Funding Council for England (UK), The Swiss Federal Institute of Technology ETH Zürich [Eidgenössische Technische Hochschule Zürich)](CH), The National Center for Supercomputing Applications at The University of Illinois at Urbana-Champaign, The Kavli Institute of Cosmological Physics at The University of Chicago, Center for Cosmology and AstroParticle Physics at The Ohio State University, Mitchell Institute for Fundamental Physics and Astronomy at The Texas A&M University, Brazil Funding Authority for Studies and Projects for Scientific and Technological Development [Financiadora de Estudos e Projetos ] (BR) , Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro [Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro](BR), The Ministry of Science and Technology [Conselho Nacional de Desenvolvimento Científico e Tecnológico and Ministério da Ciência e Tecnologia(BR), German Research Foundation [Deutsche Forschungsgemeinschaft](DE), and the collaborating institutions in the Dark Energy Survey.

The National Center for Supercomputing Applications at The University of Illinois at Urbana-Champaign provides
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DOE’s Fermi National Accelerator Laboratory is America’s premier national laboratory for particle physics and accelerator research. A Department of Energy Office of Science laboratory, Fermilab is located near Chicago, Illinois, and operated under contract by the Fermi Research Alliance LLC, a joint partnership between The University of Chicago and The Universities Research Association, Inc .

The DOE Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time.