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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
NASA Administrator Bill Nelson, left, and Deputy Administrator Pam Melroy, right, present Bob Cabana, who served as a NASA associate administrator, astronaut, and a colonel in the United States Marine Corps, the President’s Award for Distinguished Federal Civilian Service, recognizing his exceptional achievements and public service to the nation, Jan. 10, 2025, at the Mary W. Jackson NASA Headquarters in Washington. The award, signed by President Biden, is the highest honor the federal government can grant to a federal civilian employee.Credit: NASA/Bill Ingalls Robert Cabana, who served as a NASA associate administrator, astronaut, and a colonel in the United States Marine Corps, received the President’s Award for Distinguished Federal Civilian Service, recognizing his exceptional achievements and public service to the nation. The award, signed by President Biden, is the highest honor the federal government can grant to a federal civilian employee.
NASA Administrator Bill Nelson and Deputy Administrator Pam Melroy presented Cabana with the award during a ceremony at NASA Headquarters in Washington on Jan. 10. Cabana most recently served as NASA’s associate administrator, which is the agency’s highest ranking civil servant, from 2021 until he retired from the agency at the end of 2023.
“A true public servant, Bob has spent his entire career in service to his country. I can think of no one more deserving of this rare honor than Bob,” said Nelson. “From his time as a naval aviator to his role as associate administrator of NASA, Bob has dedicated his life to improving his country. I join with President Biden in thanking Bob for his dedication and commitment.”
The award recognized Cabana for his roles as a Marine aviator, test pilot, astronaut and becoming the first American to enter the International Space Station. He was further recognized for continuing to push for the bounds of the possible, launching the James Webb Space Telescope, the Artemis I mission and the Orion spacecraft which will send humans back to the Moon for the first time in decades.
As a NASA astronaut, Cabana flew in space four times, including twice as commander. His final space shuttle flight in 1998 was the first International Space Station assembly mission. Cabana also was the director of the agency’s Kennedy Space Center in Florida for more than a decade. There he led its transition from retirement of the space shuttle to a multi-user spaceport once again launching NASA astronauts to low Earth orbit, and for the first time, doing so with commercial partners.
As NASA associate administrator, Cabana led the agency’s 10 center directors, as well as the mission directorate associate administrators at NASA Headquarters. He was the agency’s chief operating officer for more than 18,000 employees and oversaw an annual budget of more than $25 billion.
Cabana was selected as an astronaut candidate in June 1985 and completed training in July 1986. He logged 38 days in space during four shuttle missions. Cabana was a pilot aboard space shuttle Discovery on both the STS-41 mission in October 1990 that deployed the Ulysses spacecraft and the STS-53 mission in December 1992. He was the mission commander aboard space shuttle Columbia for the STS-65 mission in July 1994 that conducted experiments as part of the second International Microgravity Laboratory mission. He commanded space shuttle Endeavour for the STS-88 mission in December 1998.
Cabana was appointed a member of the Federal Senior Executive Service in 2000 and served in numerous senior management positions at NASA’s Johnson Space Center in Houston, ultimately becoming deputy director. He was named director of NASA’s Stennis Space Center in Mississippi in October 2007 and a year later was selected as NASA Kennedy director.
Born in Minneapolis, Cabana graduated from the U.S. Naval Academy in 1971 with a bachelor’s degree in mathematics. He became a naval aviator and graduated with distinction from the U.S. Naval Test Pilot School in 1981. In his career, Cabana logged over 7,000 hours in more than 50 different kinds of aircraft. He retired as a colonel from the U.S. Marine Corps in September 2000.
In addition to receiving the President’s Award for Distinguished Federal Service, Cabana’s accomplishments have been recognized with induction into the Astronaut Hall of Fame and being named an Associate Fellow in the American Institute of Aeronautics and Astronautics and a Fellow in the Society of Experimental Test Pilots. He has received numerous personal awards and decorations, including the Distinguished Flying Cross and the Presidential Distinguished Rank Award. He also is a recipient of the Rotary National Award for Space Achievement’s National Space Trophy.
For Cabana’s full bio, visit:
https://go.nasa.gov/3u9hGB2
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Meira Bernstein / Jennifer Dooren
Headquarters, Washington
202-615-1747 / 202-358-1600
meira.b.bernstein@nasa.gov / jennifer.m.dooren@nasa.gov
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Last Updated Jan 13, 2025 EditorJessica TaveauLocationNASA Headquarters Related Terms
Robert D. Cabana Bill Nelson Johnson Space Center Kennedy Space Center NASA Headquarters Pamela A. Melroy Space Shuttle Stennis Space Center View the full article
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By NASA
4 min read
Astronaut Set to Patch NASA’s X-ray Telescope Aboard Space Station
NASA astronaut Nick Hague will install patches to the agency’s NICER (Neutron star Interior Composition Explorer) X-ray telescope on the International Space Station as part of a spacewalk scheduled for Jan. 16. Hague, along with astronaut Suni Williams, will also complete other tasks during the outing.
NICER will be the first NASA observatory repaired on-orbit since the last servicing mission for the Hubble Space Telescope in 2009.
Hague and other astronauts, including Don Pettit, who is also currently on the space station, rehearsed the NICER patch procedures in the NBL (Neutral Buoyancy Laboratory), a 6.2-million-gallon indoor pool at NASA’s Johnson Space Center in Houston, in 2024.
NASA astronaut Nick Hague holds a patch for NICER (Neutron star Interior Composition Explorer) at the end of a T-handle tool during a training exercise on May 16, 2024, in the NBL (Neutral Buoyancy Laboratory) at NASA’s Johnson Space Center in Houston. NASA/NBL Dive Team Astronaut Nick Hague removes a patch from the caddy using a T-handle tool during a training exercise in the NBL at NASA Johnson on May 16, 2024. The booklet on his wrist has a schematic of the NICER telescope and where the patches will go.NASA/NBL Dive Team “We use the NBL to mimic, as much as possible, the conditions astronauts will experience while preforming a task during a spacewalk,” said Lucas Widner, a flight controller at KBR and NASA Johnson who ran the NICER NBL sessions. “Most projects outside the station focus on maintenance and upgrades to components like solar panels. It’s been exciting for all of us to be part of getting a science mission back to normal operations.”
From its perch near the space station’s starboard solar array, NICER studies the X-ray sky, including erupting galaxies, black holes, superdense stellar remnants called neutron stars, and even comets in our solar system.
But in May 2023, NICER developed a “light leak.” Sunlight began entering the telescope through several small, damaged areas in the telescope’s thin thermal shields. During the station’s daytime, the light reaches the X-ray detectors, saturating sensors and interfering with NICER’s measurements of cosmic objects. The mission team altered their daytime observing strategy to mitigate the effect.
UAE (United Arab Emirates) astronaut Sultan Alneyadi captured this view of NICER from a window in the space station’s Poisk Mini-Research Module 2 in July 2023. Photos like this one helped the NICER team map the damage to the telescope’s thermal shields.NASA/Sultan Alneyadi Some of NICER’s damaged thermal shields (circled) are visible in this photograph.NASA/Sultan Alneyadi The team also developed a plan to cover the largest areas of damage using wedge-shaped patches. Hague will slide the patches into the telescope’s sunshades and lock them into place.
“We designed the patches so they could be installed either robotically or by an astronaut,” said Steve Kenyon, NICER’s mechanical engineering lead at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “They’re installed using a tool called a T-handle that the astronauts are already familiar with.”
The NBL contains life-size mockups of sections of the space station. Under the supervision of a swarm of scuba divers, a pair of astronauts rehearse exiting and returning through an airlock, traversing the outside of the station, and completing tasks.
For the NICER repair, the NBL team created a full-scale model of NICER and its surroundings near the starboard solar array. Hague, Pettit, and other astronauts practiced taking the patches out of their caddy, inserting them into the sunshades, locking them into place, and verifying they were secure.
The task took just under an hour each time, which included the time astronauts needed to travel to NICER, set up their tools, survey the telescope for previously undetected damage, complete the repair, and clean up their tools.
Practice runs also provided opportunities for the astronauts to troubleshoot how to position themselves so they could reach NICER without touching it too often and for flight controllers to identify safety concerns around the repair.
Astronaut Don Pettit simulates taking pictures of the NICER telescope mockup during a training exercise in the NBL at NASA Johnson on May 16, 2024.NASA/NBL Dive Team Astronaut Don Pettit removes a patch from the caddy during a training exercise in the NBL at NASA Johnson on May 16, 2024.NASA/NBL Dive Team Being fully submerged in a pool is not the same as being in space, of course, so some issues that arose were “pool-isms.” For example, astronauts sometimes drifted upward while preparing to install the patches in a way unlikely to happen in space.
Members of the NICER team, including Kenyon and the mission’s principal investigator, Keith Gendreau at NASA Goddard, supported the NBL practice runs. They helped answer questions about the physical aspects of the telescope, as well as science questions from the astronauts and flight controllers. NICER is the leading source of science results on the space station.
“It was awesome to watch the training sessions and be able to debrief with the astronauts afterward,” Gendreau said. “There isn’t usually a lot of crossover between astrophysics science missions and human spaceflight. NICER will be the first X-ray telescope serviced by astronauts. It’s been an exciting experience, and we’re all looking forward to the spacewalk where it will all come together.”
The NICER telescope is an Astrophysics Mission of Opportunity within NASA’s Explorers Program, which provides frequent flight opportunities for world-class scientific investigations from space utilizing innovative, streamlined, and efficient management approaches within the heliophysics and astrophysics science areas. NASA’s Space Technology Mission Directorate supported the SEXTANT component of the mission, demonstrating pulsar-based spacecraft navigation.
Download high-resolution images and videos of NICER at NASA’s Scientific Visualization Studio. By Jeanette Kazmierczak
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Claire Andreoli
301-286-1940
claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Jan 08, 2025 Related Terms
Astrophysics Black Holes Goddard Space Flight Center International Space Station (ISS) ISS Research Johnson Space Center Neutron Stars NICER (Neutron star Interior Composition Explorer) Pulsars The Universe View the full article
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By NASA
NASA astronaut and Expedition 72 Flight Engineer Don Pettit points a camera outside a window on the International Space Station’s Poisk module for a sun photography session. (Credit: NASA) Students from Hawthorne Elementary School in Boise, Idaho, will have the chance to hear NASA astronaut Don Pettit answer their prerecorded science, technology, engineering, and math (STEM) related questions from aboard the International Space Station.
Watch the 20-minute space-to-Earth call at 12:30 p.m. EST Friday, Jan. 10, on NASA+ and learn how to watch NASA content on various platforms, including social media.
Media interested in covering the event must RSVP by 5 p.m., Tuesday, Jan. 7, to
Dan Hollar at dan.hollar@boiseschools.org or 208-854-4064.
For more than 24 years, astronauts have continuously lived and worked aboard the space station, testing technologies, performing science, and developing skills needed to explore farther from Earth. Astronauts aboard the orbiting laboratory communicate with NASA’s Mission Control Center in Houston 24 hours a day through SCaN’s (Space Communications and Navigation) Near Space Network.
Important research and technology investigations taking place aboard the space station benefit people on Earth and lays the groundwork for other agency missions. As part of NASA’s Artemis campaign, the agency will send astronauts to the Moon to prepare for future human exploration of Mars; inspiring Artemis Generation explorers and ensuring the United States continues to lead in space exploration and discovery.
See videos and lesson plans highlighting space station research at:
https://www.nasa.gov/stemonstation
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Abbey Donaldson
Headquarters, Washington
202-358-1600
Abbey.a.donaldson@nasa.gov
Sandra Jones
Johnson Space Center, Houston
281-483-5111
sandra.p.jones@nasa.gov
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By NASA
Artist’s concept depicts new research that has expanded our understanding of exoplanet WASP-69 b’s “tail.” NASA/JPL-Caltech/R. Hurt (IPAC) The Planet
WASP-69 b
The Discovery
The exoplanet WASP-69 b has a “tail,” leaving a trail of gas in its wake.
Key Takeaway
WASP-69 b is slowly losing its atmosphere as light hydrogen and helium particles in the planet’s outer atmosphere escape the planet over time. But those gas particles don’t escape evenly around the planet, instead they are swept into a tail of gas by the stellar wind coming from the planet’s star.
Details
Hot Jupiters like WASP-69 b are super-hot gas giants orbiting their host stars closely. When radiation coming from a star heats up a planet’s outer atmosphere, the planet can experience photoevaporation, a process in which lightweight gases like hydrogen and helium are heated by this radiation and launched outward into space. Essentially, WASP-69 b’s star strips gas from the planet’s outer atmosphere over time.
What’s more, something called the stellar wind can shape this escaping gas into an exoplanetary tail.
The stellar wind is a continuous stream of charged particles that flow outwards into space from a star’s outer atmosphere, or corona. On Earth, the Sun’s stellar wind interacts with our planet’s magnetic field which can create beautiful auroras like the Northern Lights.
On WASP-69 b, the stellar wind coming from its host star actually shapes the gas escaping from the planet’s outer atmosphere. So, instead of gas just escaping evenly around the planet, “strong stellar winds can sculpt that outflow in tails that trail behind the planet,” said lead author Dakotah Tyler, an astrophysicist at the University of California, Los Angeles, likening this gaseous tail to a comet’s tail.
Because this tail is created by the stellar wind, however, that means it’s subject to change.
“If the stellar wind were to taper down, then you could imagine that the planet is still losing some of its atmosphere, but it just isn’t getting shaped into the tail,” Tyler said, adding that, without the stellar wind, that gas escaping on all sides of the planet would be spherical and symmetrical. “But if you crank up the stellar wind, that atmosphere then gets sculpted into a tail.”
Tyler likened the process to a windsock blowing in the breeze, with the sock forming a more structured shape when the wind picks up and it fills with air.
The tail that Tyler and his research team observed on WASP-69 b extended more than 7.5 times the radius of the planet, or over 350,000 miles. But it’s possible that the tail is even longer. The team had to end observations with the telescope before the tail’s signal disappeared, so this measurement is a lower limit on the tail’s true length at the time.
However, keep in mind that because the tail is influenced by the stellar wind, changes in the stellar wind could change the tail’s size and shape over time. Additionally changes in the stellar wind influence the tail’s size and shape, but since the tail is visible when illuminated by starlight, changes in stellar activity can also affect tail observations.
Exoplanet tails are still a bit mysterious, especially because they are subject to change. The study of exoplanet tails could help scientists to better understand how these tails form as well as the ever-changing relationship between the stellar and planetary atmospheres. Additionally, because these exoplanetary tails are shaped by stellar activity, they could serve as indicators of stellar behavior over time. This could be helpful for scientists as they seek to learn more about the stellar winds of stars other than the star we know the most about, our very own Sun.
Fun Facts
WASP-69 b is losing a lot of gas — about 200,000 tons per second. But it’s losing this gaseous atmosphere very slowly — so slowly in fact that there is no danger of the planet being totally stripped or disappearing. In general, every billion years, the planet is losing an amount of material that equals the mass of planet Earth.
The solar system that WASP-69 b inhabits is about 7 billion years old, so even though the rate of atmosphere loss will vary over time, you might estimate that this planet has lost the equivalent of seven Earths (in mass) of gas over that period.
The Discoverers
A team of scientists led by Dakotah Tyler of the University of California, Los Angeles published a paper in January, 2024 on their discovery, “WASP-69b’s Escaping Envelope Is Confined to a Tail Extending at Least 7 Rp,” in the journal, “The Astrophysical Journal.” The observations described in this paper were made by Keck/NIRSPEC (NIRSPEC is a spectrograph designed for Keck II).
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