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Starry-Eyed Hubble Celebrates 20 Years of Awe and Discovery
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Explore This Section Exoplanets Home Exoplanets Overview Exoplanets Facts Types of Exoplanets Stars What is the Universe Search for Life The Big Questions Are We Alone? Can We Find Life? The Habitable Zone Why We Search Target Star Catalog Discoveries Discoveries Dashboard How We Find and Characterize Missions People Exoplanet Catalog Immersive The Exoplaneteers Exoplanet Travel Bureau 5 Ways to Find a Planet Strange New Worlds Universe of Monsters Galaxy of Horrors News Stories Blog Resources Get Involved Glossary Eyes on Exoplanets Exoplanet Watch More Multimedia ExEP This artist’s concept pictures the planets orbiting Barnard’s Star, as seen from close to the surface of one of them. Image credit: International Gemini Observatory/NOIRLab/NSF/AURA/P. Marenfeld The Discovery
Four rocky planets much smaller than Earth orbit Barnard’s Star, the next closest to ours after the three-star Alpha Centauri system. Barnard’s is the nearest single star.
Key Facts
Barnard’s Star, six light-years away, is notorious among astronomers for a history of false planet detections. But with the help of high-precision technology, the latest discovery — a family of four — appears to be solidly confirmed. The tiny size of the planets is also remarkable: Capturing evidence of small worlds at great distance is a tall order, even using state-of-the-art instruments and observational techniques.
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Watching for wobbles in the light from a star is one of the leading methods for detecting exoplanets — planets orbiting other stars. This “radial velocity” technique tracks subtle shifts in the spectrum of starlight caused by the gravity of a planet pulling its star back and forth as the planet orbits. But tiny planets pose a major challenge: the smaller the planet, the smaller the pull. These four are each between about a fifth and a third as massive as Earth. Stars also are known to jitter and quake, creating background “noise” that potentially could swamp the comparatively quiet signals from smaller, orbiting worlds.
Astronomers measure the back-and-forth shifting of starlight in meters per second; in this case the radial velocity signals from all four planets amount to faint whispers — from 0.2 to 0.5 meters per second (a person walks at about 1 meter per second). But the noise from stellar activity is nearly 10 times larger at roughly 2 meters per second.
How to separate planet signals from stellar noise? The astronomers made detailed mathematical models of Barnard’s Star’s quakes and jitters, allowing them to recognize and remove those signals from the data collected from the star.
The new paper confirming the four tiny worlds — labeled b, c, d, and e — relies on data from MAROON-X, an “extreme precision” radial velocity instrument attached to the Gemini Telescope on the Maunakea mountaintop in Hawaii. It confirms the detection of the “b” planet, made with previous data from ESPRESSO, a radial velocity instrument attached to the Very Large Telescope in Chile. And the new work reveals three new sibling planets in the same system.
Fun Facts
These planets orbit their red-dwarf star much too closely to be habitable. The closest planet’s “year” lasts a little more than two days; for the farthest planet, it’s is just shy of seven days. That likely makes them too hot to support life. Yet their detection bodes well in the search for life beyond Earth. Scientists say small, rocky planets like ours are probably the best places to look for evidence of life as we know it. But so far they’ve been the most difficult to detect and characterize. High-precision radial velocity measurements, combined with more sharply focused techniques for extracting data, could open new windows into habitable, potentially life-bearing worlds.
Barnard’s star was discovered in 1916 by Edward Emerson Barnard, a pioneering astrophotographer.
The Discoverers
An international team of scientists led by Ritvik Basant of the University of Chicago published their paper on the discovery, “Four Sub-Earth Planets Orbiting Barnard’s Star from MAROON-X and ESPRESSO,” in the science journal, “The Astrophysical Journal Letters,” in March 2025. The planets were entered into the NASA Exoplanet Archive on March 13, 2025.
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Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Posters Hubble on the NASA App Glossary More 35th Anniversary Online Activities 5 Min Read 20-Year Hubble Study of Uranus Yields New Atmospheric Insights
The image columns show the change of Uranus for the four years that STIS observed Uranus across a 20-year period. Over that span of time, the researchers watched the seasons of Uranus as the south polar region darkened going into winter shadow while the north polar region brightened as northern summer approaches. Credits:
NASA, ESA, Erich Karkoschka (LPL) The ice-giant planet Uranus, which travels around the Sun tipped on its side, is a weird and mysterious world. Now, in an unprecedented study spanning two decades, researchers using NASA’s Hubble Space Telescope have uncovered new insights into the planet’s atmospheric composition and dynamics. This was possible only because of Hubble’s sharp resolution, spectral capabilities, and longevity.
The team’s results will help astronomers to better understand how the atmosphere of Uranus works and responds to changing sunlight. These long-term observations provide valuable data for understanding the atmospheric dynamics of this distant ice giant, which can serve as a proxy for studying exoplanets of similar size and composition.
When Voyager 2 flew past Uranus in 1986, it provided a close-up snapshot of the sideways planet. What it saw resembled a bland, blue-green billiard ball. By comparison, Hubble chronicled a 20-year story of seasonal changes from 2002 to 2022. Over that period, a team led by Erich Karkoschka of the University of Arizona, and Larry Sromovsky and Pat Fry from the University of Wisconsin used the same Hubble instrument, STIS (the Space Telescope Imaging Spectrograph), to paint an accurate picture of the atmospheric structure of Uranus.
Uranus’ atmosphere is mostly hydrogen and helium, with a small amount of methane and traces of water and ammonia. The methane gives Uranus its cyan color by absorbing the red wavelengths of sunlight.
The Hubble team observed Uranus four times in the 20-year period: in 2002, 2012, 2015, and 2022. They found that, unlike conditions on the gas giants Saturn and Jupiter, methane is not uniformly distributed across Uranus. Instead, it is strongly depleted near the poles. This depletion remained relatively constant over the two decades. However, the aerosol and haze structure changed dramatically, brightening significantly in the northern polar region as the planet approaches its northern summer solstice in 2030.
The image columns show the change of Uranus for the four years that STIS observed Uranus across a 20-year period. Over that span of time, the researchers watched the seasons of Uranus as the south polar region darkened going into winter shadow while the north polar region brightened as northern summer approaches. NASA, ESA, Erich Karkoschka (LPL) Uranus takes a little over 84 Earth years to complete a single orbit of the Sun. So, over two decades, the Hubble team has only seen mostly northern spring as the Sun moves from shining directly over Uranus’ equator toward shining almost directly over its north pole in 2030. Hubble observations suggest complex atmospheric circulation patterns on Uranus during this period. The data that are most sensitive to the methane distribution indicate a downwelling in the polar regions and upwelling in other regions.
The team analyzed their results in several ways. The image columns show the change of Uranus for the four years that STIS observed Uranus across a 20-year period. Over that span of time, the researchers watched the seasons of Uranus as the south polar region (left) darkened going into winter shadow while the north polar region (right) brightened as it began to come into a more direct view as northern summer approaches.
The top row, in visible light, shows how the color of Uranus appears to the human eye as seen through even an amateur telescope.
In the second row, the false-color image of the planet is assembled from visible and near-infrared light observations. The color and brightness correspond to the amounts of methane and aerosols. Both of these quantities could not be distinguished before Hubble’s STIS was first aimed at Uranus in 2002. Generally, green areas indicate less methane than blue areas, and red areas show no methane. The red areas are at the limb, where the stratosphere of Uranus is almost completely devoid of methane.
The two bottom rows show the latitude structure of aerosols and methane inferred from 1,000 different wavelengths (colors) from visible to near infrared. In the third row, bright areas indicate cloudier conditions, while the dark areas represent clearer conditions. In the fourth row, bright areas indicate depleted methane, while dark areas show the full amount of methane.
At middle and low latitudes, aerosols and methane depletion have their own latitudinal structure that mostly did not change much over the two decades of observation. However, in the polar regions, aerosols and methane depletion behave very differently.
In the third row, the aerosols near the north pole display a dramatic increase, showing up as very dark during early northern spring, turning very bright in recent years. Aerosols also seem to disappear at the left limb as the solar radiation disappeared. This is evidence that solar radiation changes the aerosol haze in the atmosphere of Uranus. On the other hand, methane depletion seems to stay quite high in both polar regions throughout the observing period.
Astronomers will continue to observe Uranus as the planet approaches northern summer.
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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20 Years of Uranus Observations
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Last Updated Mar 31, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center
Contact Media Claire Andreoli
NASA’s Goddard Space Flight Center
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claire.andreoli@nasa.gov
Ann Jenkins
Space Telescope Science Institute, Baltimore, Maryland
Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
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By NASA
Explore Hubble Hubble Home Overview About Hubble The History of Hubble Hubble Timeline Why Have a Telescope in Space? Hubble by the Numbers At the Museum FAQs Impact & Benefits Hubble’s Impact & Benefits Science Impacts Cultural Impact Technology Benefits Impact on Human Spaceflight Astro Community Impacts Science Hubble Science Science Themes Science Highlights Science Behind Discoveries Hubble’s Partners in Science Universe Uncovered Explore the Night Sky Observatory Hubble Observatory Hubble Design Mission Operations Missions to Hubble Hubble vs Webb Team Hubble Team Career Aspirations Hubble Astronauts News Hubble News Hubble News Archive Social Media Media Resources Multimedia Multimedia Images Videos Sonifications Podcasts e-Books Online Activities Lithographs Fact Sheets Posters Hubble on the NASA App Glossary More 35th Anniversary Online Activities 2 min read
Hubble Spots a Chance Alignment
This NASA/ESA Hubble image features the spiral galaxy NGC 5530. ESA/Hubble & NASA, D. Thilker The subject of today’s NASA/ESA Hubble Space Telescope image is the stunning spiral galaxy NGC 5530. This galaxy is situated 40 million light-years away in the constellation Lupus, the Wolf, and classified as a ‘flocculent’ spiral, meaning its spiral arms are patchy and indistinct.
While some galaxies have extraordinarily bright centers that host a feasting supermassive black hole, the bright source near the center of NGC 5530 is not an active black hole but a star within our own galaxy, only 10,000 light-years from Earth. This chance alignment gives the appearance that the star is at the dense heart of NGC 5530.
If you pointed a backyard telescope at NGC 5530 on the evening of September 13, 2007, you would have seen another bright point of light adorning the galaxy. That night, Australian amateur astronomer Robert Evans discovered a supernova, named SN 2007IT, by comparing NGC 5530’s appearance through the telescope to a reference photo of the galaxy. While it’s remarkable to discover even one supernova using this painstaking method, Evans has in fact discovered more than 40 supernovae this way! This particular discovery was truly serendipitous: it’s likely that the light from the supernova completed its 40-million-year journey to Earth just days before Evans spotted the explosion.
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Last Updated Mar 28, 2025 Editor Andrea Gianopoulos Location NASA Goddard Space Flight Center Related Terms
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Since its 1990 launch, the Hubble Space Telescope has changed our fundamental understanding of the universe.
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On March 24, 1975, the last in a long line of super successful Saturn rockets rolled out from the vehicle assembly building to Launch Pad 39B at NASA’s Kennedy Space Center in Florida. The Saturn IB rocket for the Apollo-Soyuz Test Project was the 19th in the Saturn class stacked in the assembly building, beginning in 1966 with the Saturn V 500F facilities checkout vehicle. Thirteen flight Saturn V rockets followed, 12 to launch Apollo spacecraft and one to place the Skylab space station into orbit. In addition, workers stacked four flight Saturn IB rockets, three to launch crews to Skylab and one for Apollo-Soyuz, plus another for the Skylab rescue vehicle that was not needed and never launched. Previously, workers stacked Saturn I and Saturn IB rockets on the pads at Launch Complexes 34 and 37. With the successful liftoff in July 1975, the Saturn family of rockets racked up a 100 percent success rate of 32 launches.
Workers lower the Apollo command and service modules onto the spacecraft adaptor.NASA Technicians in the assembly building replace the fins on the Saturn IB rocket’s first stage. NASA Workers in the assembly building prepare to lower the spacecraft onto its Saturn IB rocket.NASA Inspections of the Saturn IB rocket’s first stage fins revealed hairline cracks in several hold-down fittings and managers ordered the replacement of all eight fins. While the cracks would not affect the flight of the rocket they bore the weight of the rocket on the mobile launcher. Workers finished the fin replacement on March 16. Engineers in Kennedy’s spacecraft operations building prepared the Apollo spacecraft for its historic space mission. By early March, they had completed checkout and assembly of the spacecraft and transported it to the assembly building on March 17 to mount it atop the Saturn IB’s second stage. Five days later, they topped off the rocket with the launch escape system.
The final Saturn IB begins its rollout from the vehicle assembly building. NASA The Saturn IB passes by the Launch Control Center. NASA Apollo astronauts Thomas Stafford, left, Vance Brand, and Donald “Deke” Slayton pose in front of their Saturn IB during the rollout.NASA On March 23, workers edged the mobile transporter carrying the Saturn IB just outside the assembly building’s High Bay 1, where engineers installed an 80-foot tall lightning mast atop the launch tower. The next morning, the stack continued its rollout to Launch Pad 39B with the prime crew of Thomas Stafford, Vance Brand, and Donald “Deke” Slayton and support crew members Robert Crippen and Richard Truly on hand to observe. About 7,500 people, including guests, dependents of Kennedy employees and NASA Tours patrons, watched as the stack moved slowly out of the assembly building on its five-mile journey to the launch pad.
Mission Control in Houston during the joint simulation with Flight Director Donald Puddy in striped shirt and a view of Mission Control in Moscow on the large screen at left. NASA A group of Soviet flight controllers in a support room in Mission Control in Houston during the joint simulation. NASA On March 20, flight controllers and crews began a series of joint simulations for the joint mission scheduled for July 1975. For the six days of simulations, cosmonauts Aleksei Leonov and Valeri Kubasov and astronauts Stafford, Brand, and Slayton participated in the activity in spacecraft simulators in their respective countries, with both control centers in Houston and outside Moscow fully staffed as if for the actual mission. The exercises simulated various phases of the mission, including the respective launches, rendezvous and docking, crew transfers and joint operations, and undocking.
Astronauts Thomas Stafford, left, Vance Brand, and Donald “Deke” Slayton in a boilerplate Apollo command module preparing for the water egress training. NASA Stafford, left, Slayton, and Brand in the life raft during water egress training. NASA Astronauts Stafford, Brand and Slayton participated in a water egress training activity on March 8, completing the exercise in a water tank in Building 260 at NASA’s Johnson Space Center in Houston. The astronauts practiced egressing from their spacecraft onto a lift raft and being lifted up with the use of a Billy Pugh rescue net. They practiced wearing their flight coveralls as well as their spacesuits.
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On March 23, 1965, the United States launched the Gemini III spacecraft with astronauts Virgil “Gus” Grissom and John Young aboard, America’s first two-person spaceflight. Grissom earned the honor as the first person to enter space twice and Young as the first member of the second group of astronauts to fly in space. During their three-orbit flight they carried out the first orbital maneuvers of a crewed spacecraft, a critical step toward demonstrating rendezvous and docking. Grissom and Young brought Gemini 3 to a safe splashdown in the Atlantic Ocean. Their ground-breaking mission led the way to nine more successful Gemini missions in less than two years to demonstrate the techniques required for a Moon landing. Gemini 3 marked the last spaceflight controlled from Cape Kennedy, that function shifting permanently to a new facility in Houston.
In one of the first uses of the auditorium at the Manned Spacecraft Center, now NASA’s Johnson Space Center in Houston, managers announce the prime and backup Gemini III crews. NASA NASA astronauts Virgil “Gus” Grissom and John Young, the Gemini III prime crew. NASA Grissom, foreground, and Young in their capsule prior to launch.NASA On April 13, 1964, just five days after the uncrewed Gemini I mission, in the newly open auditorium at the Manned Spacecraft Center, now NASA’s Johnson Space Center in Houston, Director Robert Gilruth introduced the Gemini III crew to the press. NASA assigned Mercury 4 veteran Grissom and Group 2 astronaut Young as the prime crew, with Mercury 8 veteran Walter Schirra and Group 2 astronaut Thomas Stafford serving as their backups. The primary goals of Project Gemini included proving the techniques required for the Apollo Program to fulfil President John F. Kennedy’s goal of landing a man on the Moon and returning him safely to Earth before the end of the 1960s. Demonstrating rendezvous and docking between two spacecraft ranked as a high priority for Project Gemini.
Liftoff of Gemini III.NASA The uncrewed Gemini I and II missions validated the spacecraft’s design, reliability, and heat shield, clearing the way to launch Gemini III with a crew. On March 23, 1965, after donning their new Gemini spacesuits, Grissom and Young rode the transfer van to Launch Pad 19 at Cape Kennedy in Florida. They rode the elevator to their Gemini spacecraft atop its Titan II rocket where technicians assisted them in climbing into the capsule. At 9:24 a.m. EST, the Titan’s first stage engines ignited, and Gemini III rose from the launch pad.
The Mission Control Center at Cape Kennedy in Florida during Gemini III, controlling a human spaceflight for the final time.NASA The Mission Control Center at the Manned Spacecraft Center, now NASA’s Johnson Space Center in Houston, monitoring the Gemini III mission.NASA Five and a half minutes after launch, the Titan II’s second stage engine cut off and the spacecraft separated to begin its orbital journey. Grissom became the first human to enter space a second time. While engineers monitored the countdown from the Launch Pad 19 blockhouse, once in orbit flight controllers in the Mission Control Center at the Cape took over. Controllers in the new Mission Control Center at the Manned Spacecraft Center, now the Johnson Space Center in Houston, staffed consoles and monitored the mission in a backup capacity. Beginning with Gemini IV, control of all American human spaceflights shifted permanently to the Houston facility.
Gemini III entered an orbit of 100 miles by 139 miles above the Earth. Near the end of the first orbit, while passing over Texas, Grissom and Young fired their spacecraft’s thrusters for one minute, 14 seconds. “They appear to be firing good,” said Young, confirming the success of the maneuver. The change in velocity adjusted their orbit to 97 miles by 105 miles. A second burn 45 minutes later altered the orbital inclination by 0.02 degrees. Another task for the crew involved testing new food and packaging developed for Gemini. As an off-the-menu item, Young had stowed a corned beef on rye sandwich in his suit pocket before flight, and both he and Grissom took a bite before stowing it away, concerned about crumbs from the sandwich floating free in the cabin.
Shortly after splashdown, Gemini III astronaut Virgil “Gus” Grissom exits the spacecraft as crewmate John Young waits in the life raft. NASA Sailors hoist the Gemini III spacecraft aboard the prime recovery ship U.S.S. Intrepid.NASA Young, left, and Grissom stand with their spacecraft aboard Intrepid. NASA Near the end of their third revolution, Grissom and Young prepared for the retrofire burn to bring them out of orbit. They oriented Gemini III with its blunt end facing forward and completed a final orbital maneuver to lower the low point of their orbit to 45 miles, ensuring reentry even if the retrorockets failed to fire. They jettisoned the rearmost adapter section, exposing the retrorockets that fired successfully, bringing the spacecraft out of orbit. They jettisoned the retrograde section, exposing Gemini’s heat shield. Minutes later, they encountered the upper layers of Earth’s atmosphere at 400,000 feet, and he buildup of ionized gases caused a temporary loss of communication between the spacecraft and Mission Control. At 50,000 feet, Grissom deployed the drogue parachute to stabilize and slow the spacecraft, followed by the main parachute at 10,600 feet. Splashdown occurred in the Atlantic Ocean near Grand Turk Island, about 52 miles short of the planned point, after a flight of 4 hours, 52 minutes, 31 seconds.
Gemini III astronauts Virgil “Gus” Grissom, left, and John Young upon their return to Cape Kennedy in Florida. NASA Grissom and Young at the postflight press conference. NASA The welcome home ceremony for Grissom and Young at the Manned Spacecraft Center, now NASA’s Johnson Space Center in Houston.NASA A helicopter recovered Grissom and Young and delivered them to the deck of the U.S.S. Intrepid, arriving there one hour and 12 minutes after splashdown. On board the carrier, the astronauts received a medical checkup and a telephone call from President Lyndon B. Johnson. The ship sailed to pick up the spacecraft and sailors hoisted it aboard less than three hours after landing. The day after splashdown, Grissom and Young flew to Cape Kennedy for debriefings, a continuation of the medical examinations begun on the carrier, and a press conference. Following visits to the White House, New York, and Chicago, the astronauts returned home to Houston on March 31. The next day, Gilruth welcomed them back to the Manned Spacecraft Center, where in front of the main administration building, workers raised an American flag that Grissom and Young had carried on their mission. That flag flew during every subsequent Gemini mission.
During the Gemini III welcome home ceremony in front of the main administration building at the Manned Spacecraft Center, now NASA’s Johnson Space Center in Houston, workers raise an American flag that the astronauts had carried on their mission. NASA
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