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STScI Astronomers Nancy Levenson and David Soderblom Elected AAAS Fellows
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By NASA
5 min read
Astronomers Map Stellar ‘Polka Dots’ Using NASA’s TESS, Kepler
Scientists have devised a new method for mapping the spottiness of distant stars by using observations from NASA missions of orbiting planets crossing their stars’ faces. The model builds on a technique researchers have used for decades to study star spots.
By improving astronomers’ understanding of spotty stars, the new model — called StarryStarryProcess — can help discover more about planetary atmospheres and potential habitability using data from telescopes like NASA’s upcoming Pandora mission.
“Many of the models researchers use to analyze data from exoplanets, or worlds beyond our solar system, assume that stars are uniformly bright disks,” said Sabina Sagynbayeva, a graduate student at Stony Brook University in New York. “But we know just by looking at our own Sun that stars are more complicated than that. Modeling complexity can be difficult, but our approach gives astronomers an idea of how many spots a star might have, where they are located, and how bright or dark they are.”
A paper describing StarryStarryProcess, led by Sagynbayeva, published Monday, August 25, in The Astrophysical Journal.
Watch to learn how a new tool uses data from exoplanets, worlds beyond our solar system, to tell us about their polka-dotted stars.
NASA’s Goddard Space Flight Center
Download images and videos through NASA’s Scientific Visualization Studio.
NASA’s TESS (Transiting Exoplanet Survey Satellite) and now-retired Kepler Space Telescope were designed to identify planets using transits, dips in stellar brightness caused when a planet passes in front of its star.
These measurements reveal how the star’s light varies with time during each transit, and astronomers can arrange them in a plot astronomers call a light curve. Typically, a transit light curve traces a smooth sweep down as the planet starts passing in front of the star’s face. It reaches a minimum brightness when the world is fully in front of the star and then rises smoothly as the planet exits and the transit ends.
By measuring the time between transits, scientists can determine how far the planet lies from its star and estimate its surface temperature. The amount of missing light from the star during a transit can reveal the planet’s size, which can hint at its composition.
Every now and then, though, a planet’s light curve appears more complicated, with smaller dips and peaks added to the main arc. Scientists think these represent dark surface features akin to sunspots seen on our own Sun — star spots.
The Sun’s total number of sunspots varies as it goes through its 11-year solar cycle. Scientists use them to determine and predict the progress of that cycle as well as outbreaks of solar activity that could affect us here on Earth.
Similarly, star spots are cool, dark, temporary patches on a stellar surface whose sizes and numbers change over time. Their variability impacts what astronomers can learn about transiting planets.
Scientists have previously analyzed transit light curves from exoplanets and their host stars to look at the smaller dips and peaks. This helps determine the host star’s properties, such as its overall level of spottiness, inclination angle of the planet’s orbit, the tilt of the star’s spin compared to our line of sight, and other factors. Sagynbayeva’s model uses light curves that include not only transit information, but also the rotation of the star itself to provide even more detailed information about these stellar properties.
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This artist’s concept illustrates the varying brightness of star with a transiting planet and several star spots. NASA’s Goddard Space Flight Center “Knowing more about the star in turn helps us learn even more about the planet, like a feedback loop,” said co-author Brett Morris, a senior software engineer at the Space Telescope Science Institute in Baltimore. “For example, at cool enough temperatures, stars can have water vapor in their atmospheres. If we want to look for water in the atmospheres of planets around those stars — a key indicator of habitability — we better be very sure that we’re not confusing the two.”
To test their model, Sagynbayeva and her team looked at transits from a planet called TOI 3884 b, located around 141 light-years away in the northern constellation Virgo.
Discovered by TESS in 2022, astronomers think the planet is a gas giant about five times bigger than Earth and 32 times its mass.
The StarryStarryProcess analysis suggests that the planet’s cool, dim star — called TOI 3384 — has concentrations of spots at its north pole, which also tips toward Earth so that the planet passes over the pole from our perspective.
Currently, the only available data sets that can be fit by Sagynbayeva’s model are in visible light, which excludes infrared observations taken by NASA’s James Webb Space Telescope. But NASA’s upcoming Pandora mission will benefit from tools like this one. Pandora, a small satellite developed through NASA’s Astrophysics Pioneers Program, will study the atmospheres of exoplanets and the activity of their host stars with long-duration multiwavelength observations. The Pandora mission’s goal is to determine how the properties of a star’s light differs when it passes through a planet’s atmosphere so scientists can better measure those atmospheres using Webb and other missions.
“The TESS satellite has discovered thousands of planets since it launched in 2018,” said Allison Youngblood, TESS project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “While Pandora will study about 20 worlds, it will advance our ability to pick out which signals come from stars and which come from planets. The more we understand the individual parts of a planetary system, the better we understand the whole — and our own.”
Facebook logo @NASAUniverse @NASAUniverse Instagram logo @NASAUniverse By Jeanette Kazmierczak
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contact:
Alise Fisher
202-358-2546
alise.m.fisher@nasa.gov
NASA Headquarters, Washington
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Last Updated Aug 25, 2025 Related Terms
Astrophysics Exoplanet Atmosphere Exoplanets Galaxies, Stars, & Black Holes Galaxies, Stars, & Black Holes Research Goddard Space Flight Center Kepler / K2 Stars TESS (Transiting Exoplanet Survey Satellite) The Universe View the full article
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By European Space Agency
Astronomers have discovered a huge filament of hot gas bridging four galaxy clusters. At 10 times as massive as our galaxy, the thread could contain some of the Universe’s ‘missing’ matter, addressing a decades-long mystery.
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By NASA
3 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Earth scientist Compton J. Tucker has been elected to the National Academy of Sciences for his work creating innovative tools to track the planet’s changing vegetation from space. It’s research that has spanned nearly 50 years at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, where he is a visiting scientist after retiring in March.
Tucker’s research began with identifying wavelengths of light that are absorbed or reflected as plants undergo photosynthesis, and has evolved into calculating the health and productivity of vegetation over time with satellites.
“I’m honored and surprised,” Tucker said of his election. “There were opportunities at the Goddard Space Flight Center that have enabled this work that couldn’t be found elsewhere. There were people who built satellites, who understood satellite data, and had the computer code to process it. All the work I’ve done has been part of a team, with other people contributing in different ways. Working at NASA is a team effort of science and discovery that’s fun and intellectually rewarding.”
Earth scientist Compton Tucker, who has studied remote sensing of vegetation at NASA Goddard for 50 years, has been elected to the National Academy of Sciences.Courtesy Compton Tucker Tucker earned his master’s and doctoral degrees from Colorado State University, where he worked on a National Science Foundation-funded project analyzing spectrometer data of grassland ecosystems. In 1975, he came to NASA Goddard as a postdoctoral fellow and used what he learned in his graduate work to modify the imager on National Oceanic and Atmospheric Administration (NOAA) meteorological satellites and modify Landsat’s thematic mapper instrument.
He became a civil servant at the agency in 1977, and continued work with radiometers to study vegetation – first with handheld devices, then with NOAA’s Advanced Very High Resolution Radiometer satellite instruments. He has also used data from Landsat satellites, Moderate Resolution Imaging Spectroradiometer instruments, and commercial satellites. His scientific papers have been cited 100,000 times, and one of his recent studies mapped 10 billion individual trees across Africa’s drylands to inventory carbon storage at the tree level.
“The impact of Compton Tucker’s work over the last half-century at Goddard is incredible,” said Dalia Kirschbaum, director of the Earth Sciences Division at NASA Goddard. “Among his many achievements, he essentially developed the technique of using satellites to study photosynthesis from plants, which people have used to monitor droughts, forecast crop shortages, defeat the desert locust, and even predict disease outbreaks. This is a well-deserved honor.”
Goddard scientist Compton Tucker’s work using remote sensing instruments to study vegetation involved field work in Iceland in 1976, left, graduate student research at Colorado State University in the early 1970s, top right, and analyzing satellite data stored on tape reels at Goddard.Courtesy Compton Tucker The National Academy of Sciences was proposed by Abraham Lincoln and established by Congress in 1863, charged with advising the United States on science and technology. Each year, up to 120 new members are elected “in recognition of their distinguished and continuing achievements in original research,” according to the organization.
In addition his role as a visiting scientist at Goddard, Tucker is also an adjunct professor at the University of Maryland and a consulting scholar at the University of Pennsylvania’s University Museum. He was awarded the National Air and Space Collins Trophy for Current Achievement in 1993 and the Vega Medal by the Swedish Society of Anthropology and Geography in 2014. He is a fellow of the American Association for the Advancement of Science and the American Geophysical Union, and won the Senior Executive Service Presidential Rank Award for Meritorious Service in 2017, among other honors.
By Kate Ramsayer
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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Last Updated Jun 05, 2025 EditorErica McNameeContactKate D. Ramsayerkate.d.ramsayer@nasa.govLocationNASA Goddard Space Flight Center Related Terms
Goddard Space Flight Center Earth General Landsat Moderate Resolution Imaging Spectroradiometer (MODIS) View the full article
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By NASA
NASA Dr. Nancy Grace Roman, NASA’s first Chief of Astronomy and namesake of the Nancy Grace Roman Telescope, briefs astronaut Edwin “Buzz” Aldrin on celestial objects in 1965 in Washington, D.C. Nancy Grace Roman passed away on December 25, 2018, in Germantown, Maryland at the age of 93. May 16, 2025, would have been her 100th birthday.
Prior to joining NASA in 1959, Dr. Roman was a well-respected and influential astronomer, publishing some of the most cited papers in the mid-20th century, one included in a list of 100 most influential papers in 100 years. At the agency, Roman worked to gain science support for space-based observatories. She established NASA’s scientific ballooning and airborne science, oversaw the start of the Great Observatory program with the first decade of Hubble Space Telescope development, and invested early in charge-coupled devices technology development used on Hubble – and now in digital cameras everywhere.
She was also key to the decision to link the development of the Large Space Telescope (that became Hubble) and the Space Transportation System – more commonly known as the Space Shuttle. Finally, after retiring from NASA, Dr. Roman often worked with young students in underserved communities, hoping her story and mentoring could inspire them to join humanity’s quest for knowledge in a STEM field.
Learn more about Dr. Roman.
Text credit: NASA/Jackie Townsend
Image credit: NASA
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By NASA
Wayne Johnson, who in 2012 earned the highest rank of Fellow at NASA’s Ames Research Center in California, is known worldwide as an expert in rotary wing technology. He was among those who provided help in testing Ingenuity, NASA’s Mars helicopter.NASA / Eric James NASA Ames’ Wayne Johnson Elected to 2025 Class of New Members of the National Academy of Engineering (NAE)
Dr. Wayne R. Johnson, aerospace engineer at Ames Research Center, will be inducted as a new member of the prestigious National Academy of Engineering (NAE), class of 2025, on October 5, 2025, for his 45+ years of contributions to rotorcraft analysis, tiltrotor aircraft development, emerging electric aircraft, and the Mars Helicopter development. NAE members are among the world’s most accomplished engineers from business, academia, and government and are elected by their peers. The full announcement was released to the press on February 11, 2025 from NAE and is at
https://www.nae.edu/19579/31222/20095/327741/331605/NAENewClass2025
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