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By NASA
Hubble Space TelescopeHubble Home OverviewAbout Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & BenefitsHubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts ScienceHubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky ObservatoryHubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb TeamHubble Team Career Aspirations Hubble Astronauts NewsHubble News Hubble News Archive Social Media Media Resources MultimediaMultimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Glossary Posters Hubble on the NASA App More35th Anniversary 7 Min Read NASA Celebrates Edwin Hubble’s Discovery of a New Universe
The Cepheid variable star, called V1, in the neighboring Andromeda galaxy. Credits: NASA, ESA, Hubble Heritage Team (STScI/AURA); Acknowledgement: R. Gendler For humans, the most important star in the universe is our Sun. The second-most important star is nestled inside the Andromeda galaxy. Don’t go looking for it — the flickering star is 2.2 million light-years away, and is 1/100,000th the brightness of the faintest star visible to the human eye.
Yet, a century ago, its discovery by Edwin Hubble, then an astronomer at Carnegie Observatories, opened humanity’s eyes as to how large the universe really is, and revealed that our Milky Way galaxy is just one of hundreds of billions of galaxies in the universe ushered in the coming-of-age for humans as a curious species that could scientifically ponder our own creation through the message of starlight. Carnegie Science and NASA are celebrating this centennial at the 245th meeting of the American Astronomical Society in Washington, D.C.
The seemingly inauspicious star, simply named V1, flung open a Pandora’s box full of mysteries about time and space that are still challenging astronomers today. Using the largest telescope in the world at that time, the Carnegie-funded 100-inch Hooker Telescope at Mount Wilson Observatory in California, Hubble discovered the demure star in 1923. This rare type of pulsating star, called a Cepheid variable, is used as milepost markers for distant celestial objects. There are no tape-measures in space, but by the early 20th century Henrietta Swan Leavitt had discovered that the pulsation period of Cepheid variables is directly tied to their luminosity.
Many astronomers long believed that the edge of the Milky Way marked the edge of the entire universe. But Hubble determined that V1, located inside the Andromeda “nebula,” was at a distance that far exceeded anything in our own Milky Way galaxy. This led Hubble to the jaw-dropping realization that the universe extends far beyond our own galaxy.
In fact Hubble had suspected there was a larger universe out there, but here was the proof in the pudding. He was so amazed he scribbled an exclamation mark on the photographic plate of Andromeda that pinpointed the variable star.
In commemoration of Edwin Hubble’s discovery of a Cepheid variable class star, called V1, in the neighboring Andromeda galaxy 100 years ago, astronomers partnered with the American Association of Variable Star Observers (AAVSO) to study the star. AAVSO observers followed V1 for six months, producing a plot, or light curve, of the rhythmic rise and fall of the star’s light. Based on this data, the Hubble Space Telescope was scheduled to capture the star at its dimmest and brightest light. Edwin Hubble’s observations of V1 became the critical first step in uncovering a larger, grander universe than some astronomers imagined at the time. Once dismissed as a nearby “spiral nebula” measurements of Andromeda with its embedded Cepheid star served as a stellar milepost marker. It definitively showed that Andromeda was far outside of our Milky Way. Edwin Hubble went on to measure the distances to many galaxies beyond the Milky Way by finding Cepheid variables within those levels. The velocities of those galaxies, in turn, allowed him to determine that the universe is expanding.NASA, ESA, Hubble Heritage Team (STScI/AURA); Acknowledgment: R. Gendler As a result, the science of cosmology exploded almost overnight. Hubble’s contemporary, the distinguished Harvard astronomer Harlow Shapley, upon Hubble notifying him of the discovery, was devastated. “Here is the letter that destroyed my universe,” he lamented to fellow astronomer Cecilia Payne-Gaposchkin, who was in his office when he opened Hubble’s message.
Just three years earlier, Shapley had presented his observational interpretation of a much smaller universe in a debate one evening at the Smithsonian Museum of Natural History in Washington. He maintained that the Milky Way galaxy was so huge, it must encompass the entirety of the universe. Shapley insisted that the mysteriously fuzzy “spiral nebulae,” such as Andromeda, were simply stars forming on the periphery of our Milky Way, and inconsequential.
Little could Hubble have imagined that 70 years later, an extraordinary telescope named after him, lofted hundreds of miles above the Earth, would continue his legacy. The marvelous telescope made “Hubble” a household word, synonymous with wonderous astronomy.
Today, NASA’s Hubble Space Telescope pushes the frontiers of knowledge over 10 times farther than Edwin Hubble could ever see. The space telescope has lifted the curtain on a compulsive universe full of active stars, colliding galaxies, and runaway black holes, among the celestial fireworks of the interplay between matter and energy.
Edwin Hubble was the first astronomer to take the initial steps that would ultimately lead to the Hubble Space Telescope, revealing a seemingly infinite ocean of galaxies. He thought that, despite their abundance, galaxies came in just a few specific shapes: pinwheel spirals, football-shaped ellipticals, and oddball irregular galaxies. He thought these might be clues to galaxy evolution – but the answer had to wait for the Hubble Space Telescope’s legendary Hubble Deep Field in 1994.
The most impactful finding that Edwin Hubble’s analysis showed was that the farther the galaxy is, the faster it appears to be receding from Earth. The universe looked like it was expanding like a balloon. This was based on Hubble tying galaxy distances to the reddening of light — the redshift – that proportionally increased the father away the galaxies are.
The redshift data were first collected by Lowell Observatory astronomer Vesto Slipher, who spectroscopically studied the “spiral nebulae” a decade before Hubble. Slipher did not know they were extragalactic, but Hubble made the connection. Slipher first interpreted his redshift data an example of the Doppler effect. This phenomenon is caused by light being stretched to longer, redder wavelengths if a source is moving away from us. To Slipher, it was curious that all the spiral nebulae appeared to be moving away from Earth.
Two years prior to Hubble publishing his findings, the Belgian physicist and Jesuit priest Georges Lemaître analyzed the Hubble and Slifer observations and first came to the conclusion of an expanding universe. This proportionality between galaxies’ distances and redshifts is today termed Hubble–Lemaître’s law.
Because the universe appeared to be uniformly expanding, Lemaître further realized that the expansion rate could be run back into time – like rewinding a movie – until the universe was unimaginably small, hot, and dense. It wasn’t until 1949 that the term “big bang” came into fashion.
This was a relief to Edwin Hubble’s contemporary, Albert Einstein, who deduced the universe could not remain stationary without imploding under gravity’s pull. The rate of cosmic expansion is now known as the Hubble Constant.
Ironically, Hubble himself never fully accepted the runaway universe as an interpretation of the redshift data. He suspected that some unknown physics phenomenon was giving the illusion that the galaxies were flying away from each other. He was partly right in that Einstein’s theory of special relativity explained redshift as an effect of time-dilation that is proportional to the stretching of expanding space. The galaxies only appear to be zooming through the universe. Space is expanding instead.
Compass and scale image titled “Cepheid Variable Star V1 in M31 HST WFC3/UVIS.” Four boxes each showing a bright white star in the center surrounded by other stars. Each box has a correlating date at the bottom: Dec. 17, 2020, Dec. 21, 2010, Dec. 30, 2019, and Jan. 26, 2011. The center star in the boxes appears brighter with each passing date.NASA, ESA, Hubble Heritage Project (STScI, AURA) After decades of precise measurements, the Hubble telescope came along to nail down the expansion rate precisely, giving the universe an age of 13.8 billion years. This required establishing the first rung of what astronomers call the “cosmic distance ladder” needed to build a yardstick to far-flung galaxies. They are cousins to V1, Cepheid variable stars that the Hubble telescope can detect out to over 100 times farther from Earth than the star Edwin Hubble first found.
Astrophysics was turned on its head again in 1998 when the Hubble telescope and other observatories discovered that the universe was expanding at an ever-faster rate, through a phenomenon dubbed “dark energy.” Einstein first toyed with this idea of a repulsive form of gravity in space, calling it the cosmological constant.
Even more mysteriously, the current expansion rate appears to be different than what modern cosmological models of the developing universe would predict, further confounding theoreticians. Today astronomers are wrestling with the idea that whatever is accelerating the universe may be changing over time. NASA’s Roman Space Telescope, with the ability to do large cosmic surveys, should lead to new insights into the behavior of dark matter and dark energy. Roman will likely measure the Hubble constant via lensed supernovae.
This grand century-long adventure, plumbing depths of the unknown, began with Hubble photographing a large smudge of light, the Andromeda galaxy, at the Mount Wilson Observatory high above Los Angeles.
In short, Edwin Hubble is the man who wiped away the ancient universe and discovered a new universe that would shrink humanity’s self-perception into being an insignificant speck in the cosmos.
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope and mission operations. Lockheed Martin Space, based in Denver, also supports mission operations at Goddard. The Space Telescope Science Institute in Baltimore, which is operated by the Association of Universities for Research in Astronomy, conducts Hubble science operations for NASA.
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Edwin Hubble Hubble Views the Star That Changed the Universe The History of Hubble Facebook logo @NASAHubble @NASAHubble Instagram logo @NASAHubble Media Contact:
Claire Andreoli (claire.andreoli@nasa.gov)
NASA’s Goddard Space Flight Center, Greenbelt, MD
Ray Villard
Space Telescope Science Institute, Baltimore, MD
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Last Updated Jan 15, 2025 EditorAndrea GianopoulosLocationNASA Goddard Space Flight Center Related Terms
Andromeda Galaxy Astrophysics Astrophysics Division Goddard Space Flight Center Hubble Space Telescope 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.
Discovering a Runaway Universe
Our cosmos is growing, and that expansion rate is accelerating.
The History of Hubble
Hubble’s Night Sky Challenge
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By NASA
The ARCSTONE observatory is shown in low Earth orbit with the spectrometer viewing the Sun and Moon. The spacecraft rotates in order to view the Moon or the Sun. One of the most challenging tasks in remote sensing from space is achieving required instrument calibration accuracy on-orbit. The Moon is considered to be an excellent exoatmospheric calibration source. However, the current accuracy of the Moon as an absolute reference is limited to 5 – 10%, and this level of accuracy is inadequate to meet the challenging objective of Earth Science observations. ARCSTONE is a mission concept that provides a solution to this challenge. An orbiting spectrometer flying on a small satellite in low Earth orbit will provide lunar spectral reflectance with accuracy sufficient to establish an SI-traceable absolute lunar calibration standard for past, current, and future Earth weather and climate sensors.
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By European Space Agency
In a world first, ESA and Telesat have successfully connected a Low Earth Orbit (LEO) satellite to the ground using 5G Non-Terrestrial Network (NTN) technology in the Ka-band frequency range, marking a crucial step towards making space-based connections as simple as using a mobile phone.
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By NASA
5 Min Read NASA’s Ames Research Center Celebrates 85 Years of Innovation
The NACA Ames laboratory in 1944 Credits: NASA Ames Research Center in California’s Silicon Valley pre-dates a lot of things. The center existed before NASA – the very space and aeronautics agency it’s a critical part of today. And of all the marvelous advancements in science and technology that have fundamentally changed our lives over the last 85 years since its founding, one aspect has remained steadfast; an enduring commitment to what’s known by some on-center simply as, “an atmosphere of freedom.”
Years before breaking ground at the site that would one day become home to the world’s preeminent wind tunnels, supercomputers, simulators, and brightest minds solving some of the world’s toughest challenges, Joseph Sweetman Ames, the center’s namesake, described a sentiment that would guide decades of innovation and research:
My hope is that you have learned or are learning a love of freedom of thought and are convinced that life is worthwhile only in such an atmosphere
Joseph sweetman ames
Founding member of the N.A.C.A.
“My hope is that you have learned or are learning a love of freedom of thought and are convinced that life is worthwhile only in such an atmosphere,” he said in an address to the graduates of Johns Hopkins University in June 1935.
That spirit and the people it attracted and retained are a crucial part of how Ames, along with other N.A.C.A. research centers, ultimately made technological breakthroughs that enabled humanity’s first steps on the Moon, the safe return of spacecraft through Earth’s atmosphere, and many other discoveries that benefit our day-to-day lives.
Russell Robinson momentarily looks to the camera while supervising the first excavation at what would become Ames Research Center.NACA “In the context of my work, an atmosphere of freedom means the freedom to pursue high-risk, high-reward, innovative ideas that may take time to fully develop and — most importantly — the opportunity to put them into practice for the benefit of all,” said Edward Balaban, a researcher at Ames specializing in artificial intelligence, robotics, and advanced mission concepts.
Balaban’s career at Ames has involved a variety of projects at different stages of development – from early concept to flight-ready – including experimenting with different ways to create super-sized space telescopes in space and using artificial intelligence to help guide the path a rover might take to maximize off-world science results. Like many Ames researchers over the years, Balaban shared that his experience has involved deep collaborations across science and engineering disciplines with colleagues all over the center, as well as commercial and academic partners in Silicon Valley where Ames is nestled and beyond. This is a tradition that runs deep at Ames and has helped lead to entirely new fields of study and seeded many companies and spinoffs.
Before NASA, Before Silicon Valley: The 1939 Founding of Ames Aeronautical Laboratory “In the fields of aeronautics and space exploration the cost of entry can be quite high. For commercial enterprises and universities pursuing longer term ideas and putting them into practice often means partnering up with an organization such as NASA that has the scale and multi-disciplinary expertise to mature these ideas for real-world applications,” added Balaban.
“Certainly, the topics of inquiry, the academic freedom, and the benefit to the public good are what has kept me at Ames,” reflected Ross Beyer, a planetary scientist with the SETI Institute at Ames. “There’s not a lot of commercial incentive to study other planets, for example, but maybe there will be soon. In the meantime, only with government funding and agencies like NASA can we develop missions to explore the unknown in order to make important fundamental science discoveries and broadly share them.”
For Beyer, his boundary-breaking moment came when he searched – and found – software engineers at Ames capable and passionate about open-source software to generate accurate, high-resolution, texture-mapped, 3D terrain models from stereo image pairs. He and other teams of NASA scientists have since applied that software to study and better understand everything from changes in snow and ice characteristics on Earth, as well as features like craters, mountains, and caves on Mars or the Moon. This capability is part of the Artemis campaign, through which NASA will establish a long-term presence at the Moon for scientific exploration with commercial and international partners. The mission is to learn how to live and work away from home, promote the peaceful use of space, and prepare for future human exploration of Mars.
“As NASA and private companies send missions to the Moon, they need to plan landing sites and understand the local environment, and our software is freely available for anyone to use,” Beyer said. “Years ago, our management could easily have said ‘No, let’s keep this software to ourselves; it gives us a competitive advantage.’ They didn’t, and I believe that NASA writ large allows you to work on things and share those things and not hold them back.”
When looking forward to what the next 85 years might bring, researchers shared a belief that advancements in technology and opportunities to innovate are as expansive as space itself, but like all living things, they need a healthy atmosphere to thrive. Balaban offered, “This freedom to innovate is precious and cannot be taken for granted. It can easily fall victim if left unprotected. It is absolutely critical to retain it going forward, to ensure our nation’s continuing vitality and the strength of the other freedoms we enjoy.”
Ames Aeronautical Laboratory.NACAView the full article
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By NASA
5 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
NASA’s Stennis Space Center enjoyed an active 2024, marking several milestones and engaging in frontline activities in several key areas. A compilation video offers a look at 2024 highlights in such areas of work as propulsion testing, autonomous systems, range operations, community outreach, and STEM engagement. NASA’s Stennis Space Center near Bay St. Louis, Mississippi, celebrated propulsion testing and site operations milestones in 2024, all while inspiring the Artemis Generation and welcoming new leadership that will help NASA Stennis innovate and grow into the future.
Featured highlights show a year of progress and vision, as NASA Stennis accelerates the exploration and commercialization of space, innovates to benefit NASA and industry, and leverages assets to grow as an impactful aerospace and technology hub.
“These highlights are just a small snapshot of 2024 at NASA Stennis that show the future is bright,” Bailey said. “We have an incredibly talented and committed team of employees – and all of Mississippi can be proud of the work they do here at NASA Stennis. Together, with the Artemis Generation leading the way, we are returning to the Moon. Together, we are a part of something great.”
New Center Leadership
NASA Stennis Director John Bailey, right, and NASA Stennis Deputy Director Christine Powell stand near the United States Capitol during a visit to Washington, D.C. on Sept. 18. It marked the first visit to Capitol Hill for the center leaders since being named to their current roles. NASA/Stennis NASA Administrator Bill Nelson named John Bailey as director of NASA Stennis in April. Bailey had been serving as acting director since January 2024. “So much of NASA runs through Stennis,” said Nelson. “It is where we hone new and exciting capabilities in aerospace, technology, and deep space exploration. I am confident that John will lead the nation’s largest and premier propulsion test site to even greater success.”
Four months later in August, Bailey announced that longtime propulsion engineer/manager Christine Powell had been selected as deputy director of NASA Stennis.
Powell, the first woman selected as NASA Stennis deputy director, began her 33-year agency career as an intern at the center in 1991. She previously worked in multiple Engineering and Test Directorate roles, and most recently served as manager of the NASA Rocket Propulsion Test Program Office.
Propulsion Activity
NASA achieves a major milestone for future Artemis missions with successful completion of the second – and final – RS-25 engine certification test series April 3 on the Fred Haise Test Stand at NASA’s Stennis Space Center. NASA/Danny Nowlin NASA achieved major milestones for future Artemis missions at NASA Stennis in 2024. The NASA Stennis test team successfully completed a second – and final – RS-25 engine certification test series in April. The mission-critical series verified engine upgrades designed to enhance efficiency and reliability for future SLS (Space Launch System) missions.
NASA Stennis crews also completed a safe lift and installation of the interstage simulator component in October needed for future testing of NASA’s exploration upper stage in the B-2 position of the Thad Cochran Test Stand. The component will function during Green Run testing like the SLS interstage section that helps protect the upper stage during Artemis launches.
The test complex milestones support NASA’s goal of returning humans to the Moon and paving the way for future Mars exploration through Artemis missions.
Commercial Testing
NASA Stennis commercial tenant Rocket Lab completes a successful hot fire test of its Archimedes engine in its onsite test complex in the second half of 2024. Rocket Lab is one of numerous customers conducting test campaigns at NASA Stennis during the most recent year. Rocket Lab Already the nation’s largest multiuser propulsion test site, NASA Stennis aims to continue fueling growth of the commercial space market even further by working with aerospace companies to support a range of testing needs. In 2024, NASA Stennis supported work conducted by commercial companies such as Boeing, Blue Origin, Evolution Space, Launcher (a Vast company), Relativity Space, Rocket Lab, and Rolls-Royce.
Officials from NASA Stennis and Roll-Royce also broke ground in June for a test pad located in the NASA Stennis E Test Complex. Rolls-Royce will conduct hydrogen testing for the Pearl 15 engine, which helps power the Bombardier Global 5500 & 6500 aircraft.
ASTRA Mission Success
Members of the NASA Stennis Autonomous Systems Laboratory team monitor the center’s in-space satellite payload from the onsite ASTRA (Autonomous Satellite Technology for Resilient Applications) Payload Operation Command Center. The ASTRA payload launched aboard the Sidus Space LizzieSat-1 small satellite in March 2024, with the NASA Stennis team announcing in July that it had achieved primary mission objectives. In September, the team announced the ASTRA mission would continue during the satellite’s planned four-year mission.NASA/Danny Nowlin In July, NASA Stennis and commercial partner Sidus Space Inc. announced primary mission success for the center’s historic in-space mission – an autonomous systems payload aboard an orbiting satellite.
ASTRA (Autonomous Satellite Technology for Resilient Applications) is the on-orbit payload mission developed by NASA Stennis. The NASA Stennis ASTRA technology demonstrator is a payload rider aboard the Sidus Space premier satellite, LizzieSat-1 (LS-1) small satellite. Partner Sidus Space is responsible for all LS-1 mission operations, including launch and satellite activation, which allowed the NASA Stennis ASTRA team to complete its primary mission objectives.
NASA Stennis announced in September it will continue the center’s in-space autonomous systems payload mission through a follow-on agreement with Sidus Space Inc.
Range Operations
The Skydweller Aero solar-powered, autonomous aircraft flies above the Thad Cochran Test Stand (B-1/B-2) at NASA’s Stennis Space Center during a September 2024 test operation. Skydweller Aero has an ongoing airspace agreement with NASA Stennis to conduct test flights of its aircraft in the area. Skydweller Aero During 2024, NASA Stennis entered into an agreement with Skydweller Aero Inc. for the company to operate its solar-powered autonomous aircraft in the site’s restricted airspace, a step towards achieving a strategic center goal.
The agreement marked the first Reimbursable Space Act agreement between NASA Stennis and a commercial company to utilize the south Mississippi center’s unique capabilities to support testing and operation of uncrewed systems.
The company announced in October it had completed an initial test flight campaign of the aircraft, including two test excursions totaling 16 and 22.5 hours.
NASA Engagement
NASA Stennis representatives inspire the Artemis Generation at the NAS Pensacola Blue Angels Homecoming Air Show on Nov. 1-2. NASA’s exhibits at the air show honored 55th anniversary of the Apollo 11 lunar landing and showcased the agency’s mission to inspire the world through discovery. NASA/Stennis NASA representatives participated in a variety of outreach activities during the past year to create meaningful connections with the Artemis Generation.
The NASA ASTRO CAMP® Community Partners program, which originated at the south Mississippi NASA center, surpassed previous milestone marks in fiscal year 2024 by partnering with 373 community sites, including 50 outside the United States, to inspire youth, families, and educators.
NASA Stennis also supported STEM (science, technology, engineering, and mathematics) engagement during the year. It once again joined with NASA’s Robotics Alliance Project and co-sponsor Mississippi Power to support the second annual For the Inspiration and Recognition of Science and Technology (FIRST) Robotics Magnolia Regional Competition in Laurel, Mississippi. The event attracted 37 high school teams from eight states and one from Mexico.
The center also supported NASA activities during the 2024 total solar eclipse. In addition, it hosted informational efforts and exhibits at high-visibility events such as the 51st Annual Bayou Classic, and Essence Fest in New Orleans.
For information about NASA’s Stennis Space Center, visit:
Stennis Space Center – NASA
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Last Updated Dec 16, 2024 EditorNASA Stennis CommunicationsContactC. Lacy Thompsoncalvin.l.thompson@nasa.gov / (228) 688-3333LocationStennis Space Center Related Terms
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