NASA-Led Study Pinpoints Areas Sinking, Rising Along California Coast

The elevation changes may seem small — amounting to fractions of inches per year — but they can increase or decrease local flood risk, wave exposure, and saltwater intrusion.

Tracking and predicting sea level rise involves more than measuring the height of our oceans: Land along coastlines also inches up and down in elevation. Using California as a case study, a NASA-led team has shown how seemingly modest vertical land motion could significantly impact local sea levels in coming decades.

By 2050, sea levels in California are expected to increase between 6 and 14.5 inches (15 and 37 centimeters) higher than year 2000 levels. Melting glaciers and ice sheets, as well as warming ocean water, are primarily driving the rise. As coastal communities develop adaptation strategies, they can also benefit from a better understanding of the land’s role, the team said. The findings are being used in updated guidance for the state.

“In many parts of the world, like the reclaimed ground beneath San Francisco, the land is moving down faster than the sea itself is going up,” said lead author Marin Govorcin, a remote sensing scientist at NASA’s Jet Propulsion Laboratory in Southern California. 

The new study illustrates how vertical land motion can be unpredictable in scale and speed; it results from both human-caused factors such as groundwater pumping and wastewater injection, as well as from natural ones like tectonic activity. The researchers showed how direct satellite observations can improve estimates of vertical land motion and relative sea level rise. Current models, which are based on tide gauge measurements, cannot cover every location and all the dynamic land motion at work within a given region.

Local Changes

Researchers from JPL and the National Oceanic and Atmospheric Administration (NOAA) used satellite radar to track more than a thousand miles of California coast rising and sinking in new detail. They pinpointed hot spots — including cities, beaches, and aquifers — at greater exposure to rising seas now and in coming decades.

To capture localized motion inch by inch from space, the team analyzed radar measurements made by ESA’s (the European Space Agency’s) Sentinel-1 satellites, as well as motion velocity data from ground-based receiving stations in the Global Navigation Satellite System. Researchers compared multiple observations of the same locations made between 2015 to 2023 using a processing technique called interferometric synthetic aperture radar (InSAR).

Homing in on the San Francisco Bay Area — specifically, San Rafael, Corte Madera, Foster City, and Bay Farm Island — the team found the land subsiding at a steady rate of more than 0.4 inches (10 millimeters) per year due largely to sediment compaction. Accounting for this subsidence in the lowest-lying parts of these areas, local sea levels could rise more than 17 inches (45 centimeters) by 2050. That’s more than double the regional estimate of 7.4 inches (19 centimeters) based solely on tide gauge projections.

Not all coastal locations in California are sinking. The researchers mapped uplift hot spots of several millimeters per year in the Santa Barbara groundwater basin, which has been steadily replenishing since 2018. They also observed uplift in Long Beach, where fluid extraction and injection occur with oil and gas production.

The scientists further calculated how human-induced drivers of local land motion increase uncertainties in the sea level projections by up to 15 inches (40 centimeters) in parts of Los Angeles and San Diego counties. Reliable projections in these areas are challenging because the unpredictable nature of human activities, such as hydrocarbon production and groundwater extraction, necessitating ongoing monitoring of land motion.  

Fluctuating Aquifers, Slow-Moving Landslides

In the middle of California, in the fast-sinking parts of the Central Valley (subsiding as much as 8 inches, or 20 centimeters, per year), land motion is influenced by groundwater withdrawal. Periods of drought and precipitation can alternately draw down or inflate underground aquifers. Such fluctuations were also observed over aquifers in Santa Clara in the San Francisco Bay Area, Santa Ana in Orange County, and Chula Vista in San Diego County.

Along rugged coastal terrain like the Big Sur mountains below San Francisco and Palos Verdes Peninsula in Los Angeles, the team pinpointed local zones of downward motion associated with slow-moving landslides. In Northern California they also found sinking trends at marshlands and lagoons around San Francisco and Monterey bays, and in Sonoma County’s Russian River estuary. Erosion in these areas likely played a key factor.

Scientists, decision-makers, and the public can monitor these and other changes occurring via the JPL-led OPERA (Observational Products for End-Users from Remote Sensing Analysis) project. The OPERA project details land surface elevational changes across North America, shedding light on dynamic processes including subsidence, tectonics, and landslides.

The OPERA project will leverage additional state-of-the-art InSAR data from the upcoming NISAR (NASA-Indian Space Research Organization Synthetic Aperture Radar) mission, expected to launch within the coming months.

News Media Contacts

Jane J. Lee / Andrew Wang
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-0307 / 626-379-6874
jane.j.lee@jpl.nasa.gov / andrew.wang@jpl.nasa.gov

Written by Sally Younger

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NASA Scientists Spot Candidate for Speediest Exoplanet System

Astronomers may have discovered a scrawny star bolting through the middle of our galaxy with a planet in tow. If confirmed, the pair sets a new record for the fastest-moving exoplanet system, nearly double our solar system’s speed through the Milky Way.

The planetary system is thought to move at least 1.2 million miles per hour, or 540 kilometers per second.

“We think this is a so-called super-Neptune world orbiting a low-mass star at a distance that would lie between the orbits of Venus and Earth if it were in our solar system,” said Sean Terry, a postdoctoral researcher at the University of Maryland, College Park and NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Since the star is so feeble, that’s well outside its habitable zone. “If so, it will be the first planet ever found orbiting a hypervelocity star.”

A paper describing the results, led by Terry, was published in The Astronomical Journal on February 10.

A Star on the Move

The pair of objects was first spotted indirectly in 2011 thanks to a chance alignment. A team of scientists combed through archived data from MOA (Microlensing Observations in Astrophysics) – a collaborative project focused on a microlensing survey conducted using the University of Canterbury Mount John Observatory in New Zealand — in search of light signals that betray the presence of exoplanets, or planets outside our solar system.

Microlensing occurs because the presence of mass warps the fabric of space-time. Any time an intervening object appears to drift near a background star, light from the star curves as it travels through the warped space-time around the nearer object. If the alignment is especially close, the warping around the object can act like a natural lens, amplifying the background star’s light.

In this case, microlensing signals revealed a pair of celestial bodies. Scientists determined their relative masses (one is about 2,300 times heavier than the other), but their exact masses depend on how far away they are from Earth. It’s sort of like how the magnification changes if you hold a magnifying glass over a page and move it up and down.

“Determining the mass ratio is easy,” said David Bennett, a senior research scientist at the University of Maryland, College Park and NASA Goddard, who co-authored the new paper and led the original study in 2011. “It’s much more difficult to calculate their actual masses.”

The 2011 discovery team suspected the microlensed objects were either a star about 20 percent as massive as our Sun and a planet roughly 29 times heavier than Earth, or a nearer “rogue” planet about four times Jupiter’s mass with a moon smaller than Earth.

To figure out which explanation is more likely, astronomers searched through data from the Keck Observatory in Hawaii and ESA’s (European Space Agency’s) Gaia satellite. If the pair were a rogue planet and moon, they’d be effectively invisible – dark objects lost in the inky void of space. But scientists might be able to identify the star if the alternative explanation were correct (though the orbiting planet would be much too faint to see).

They found a strong suspect located about 24,000 light-years away, putting it within the Milky Way’s galactic bulge — the central hub where stars are more densely packed. By comparing the star’s location in 2011 and 2021, the team calculated its high speed.

But that’s just its 2D motion; if it’s also moving toward or away from us, it must be moving even faster. Its true speed may even be high enough to exceed the galaxy’s escape velocity of just over 1.3 million miles per hour, or about 600 kilometers per second. If so, the planetary system is destined to traverse intergalactic space many millions of years in the future.

“To be certain the newly identified star is part of the system that caused the 2011 signal, we’d like to look again in another year and see if it moves the right amount and in the right direction to confirm it came from the point where we detected the signal,” Bennett said.

“If high-resolution observations show that the star just stays in the same position, then we can tell for sure that it is not part of the system that caused the signal,” said Aparna Bhattacharya, a research scientist at the University of Maryland, College Park and NASA Goddard who co-authored the new paper. “That would mean the rogue planet and exomoon model is favored.”

NASA’s upcoming Nancy Grace Roman Space Telescope will help us find out how common planets are around such speedy stars, and may offer clues to how these systems are accelerated. The mission will conduct a survey of the galactic bulge, pairing a large view of space with crisp resolution.

“In this case we used MOA for its broad field of view and then followed up with Keck and Gaia for their sharper resolution, but thanks to Roman’s powerful view and planned survey strategy, we won’t need to rely on additional telescopes,” Terry said. “Roman will do it all.”

Download additional images and video from NASA’s Scientific Visualization Studio.

By Ashley Balzer
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Media contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, Md.
301-286-1940

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Newly Minted Ph.D. Studies Phytoplankton with NASA’s FjordPhyto Project

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“Travelers adventure to the wild maritime climate of Antarctica and help collect samples from one of the most data-limited regions of the world,” said Cusick.  “While on vacation, they can volunteer to join a FjordPhyto science boat experience where they spend an hour collecting water measurements like salinity, temperature, chlorophyll-a, turbidity, as well as physical samples for molecular genetics work, microscopy identification, and carbon biomass estimates. It’s a full immersion into the ecosystem and the importance of polar research!”

Cusick successfully defended her thesis on December 18, 2024, earning a Ph.D. in Oceanography from the Scripps Institution of Oceanography. Hers is the second Ph.D.  based on data from the FjordPhyto project. Martina Mascioni from FjordPhyto team earned her Ph.D. from the National University of La Plata (Argentina) in 2018.

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“It’s incredibly inspiring to be part of a program like this that’s open to non-specialist involvement,” said one volunteer, a retired biology teacher aboard the Viking Octantis ship, who continued to say, “Thank you for letting us be a part of the science and explaining so clearly why it matters to the bigger picture.”

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Euclid Discovers Einstein Ring in Our Cosmic Backyard

Euclid, an ESA (European Space Agency) mission with NASA contributions, has made a surprising discovery in our cosmic backyard: a phenomenon called an Einstein ring.

An Einstein ring is light from a distant galaxy bending to form a ring that appears aligned with a foreground object. The name honors Albert Einstein, whose general theory of relativity predicts that light will bend and brighten around objects in space.

In this way, particularly massive objects like galaxies and galaxy clusters serve as cosmic magnifying glasses, bringing even more distant objects into view. Scientists call this gravitational lensing.

Euclid Archive Scientist Bruno Altieri noticed a hint of an Einstein ring among images from the spacecraft’s early testing phase in September 2023.

“Even from that first observation, I could see it, but after Euclid made more observations of the area, we could see a perfect Einstein ring,” Altieri said. “For me, with a lifelong interest in gravitational lensing, that was amazing.”

The ring appears to encircle the center of a well-studied elliptical galaxy called NGC 6505, which is around 590 million light-years from Earth in the constellation Draco. That may sound far, but on the scale of the entire universe, NGC 6505 is close by. Thanks to Euclid’s high-resolution instruments, this is the first time that the ring of light surrounding the galaxy has been detected.  

Light from a much more distant bright galaxy, some 4.42 billion light-years away, creates the ring in the image. Gravity distorted this light as it traveled toward us. This faraway galaxy hasn’t been observed before and doesn’t yet have a name. 

“An Einstein ring is an example of strong gravitational lensing,” explained Conor O’Riordan, of the Max Planck Institute for Astrophysics, Germany, and lead author of the first scientific paper analyzing the ring. “All strong lenses are special, because they’re so rare, and they’re incredibly useful scientifically. This one is particularly special, because it’s so close to Earth and the alignment makes it very beautiful.” 

Einstein rings are a rich laboratory for scientists to explore many mysteries of the universe. For example, an invisible form of matter called dark matter contributes to the bending of light into a ring, so this is an indirect way to study dark matter. Einstein rings are also relevant to the expansion of the universe because the space between us and these galaxies — both in the foreground and the background — is stretching. Scientists can also learn about the background galaxy itself.

“I find it very intriguing that this ring was observed within a well-known galaxy, which was first discovered in 1884,” said Valeria Pettorino, ESA Euclid project scientist. “The galaxy has been known to astronomers for a very long time. And yet this ring was never observed before. This demonstrates how powerful Euclid is, finding new things even in places we thought we knew well. This discovery is very encouraging for the future of the Euclid mission and demonstrates its fantastic capabilities.” 

By exploring how the universe has expanded and formed over its cosmic history, Euclid will reveal more about the role of gravity and the nature of dark energy and dark matter. Dark energy is the mysterious force that appears to be causing the universe’s expansion. The space telescope will map more than a third of the sky, observing billions of galaxies out to 10 billion light-years. It is expected to find around 100,000 strong gravitational lenses.  

“Euclid is going to revolutionize the field with all this data we’ve never had before,” added O’Riordan.  

Although finding this Einstein ring is an achievement, Euclid must look for a different, less visually obvious type of gravitational lensing called “weak lensing” to help fulfil its quest of understanding dark energy. In weak lensing, background galaxies appear only mildly stretched or displaced. To detect this effect, scientists will need to analyze billions of galaxies.

Euclid launched from Cape Canaveral, Florida, July 1, 2023, and began its detailed survey of the sky Feb. 14, 2024. The mission is gradually creating the most extensive 3D map of the universe yet. The Einstein ring find so early in its mission indicates Euclid is on course to uncover many more secrets of the universe. 

More About Euclid

Euclid is a European mission, built and operated by ESA, with contributions from NASA. The Euclid Consortium — consisting of more than 2,000 scientists from 300 institutes in 15 European countries, the United States, Canada, and Japan — is responsible for providing the scientific instruments and scientific data analysis. ESA selected Thales Alenia Space as prime contractor for the construction of the satellite and its service module, with Airbus Defence and Space chosen to develop the payload module, including the telescope. Euclid is a medium-class mission in ESA’s Cosmic Vision Programme.

Three NASA-supported science teams contribute to the Euclid mission. In addition to designing and fabricating the sensor-chip electronics for Euclid’s Near Infrared Spectrometer and Photometer (NISP) instrument, NASA’s Jet Propulsion Laboratory led the procurement and delivery of the NISP detectors as well. Those detectors, along with the sensor chip electronics, were tested at NASA’s Detector Characterization Lab at Goddard Space Flight Center in Greenbelt, Maryland. The Euclid NASA Science Center at IPAC (ENSCI), at Caltech in Pasadena, California, will archive the science data and support U.S.-based science investigations. JPL is a division of Caltech.

Media Contacts

Elizabeth Landau
Headquarters, Washington
202-358-0845
elandau@nasa.gov

Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.
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Elizabeth R. Landau

February’s Night Sky Notes: How Can You Help Curb Light Pollution?

Light pollution has long troubled astronomers, who generally shy away from deep sky observing under full Moon skies. The natural light from a bright Moon floods the sky and hides views of the Milky Way, dim galaxies and nebula, and shooting stars. In recent years, human-made light pollution has dramatically surpassed the interference of even a bright full Moon, and its effects are now noticeable to a great many people outside of the astronomical community. Harsh, bright white LED streetlights, while often more efficient and long-lasting, often create unexpected problems for communities replacing their old street lamps. Some notable concerns are increased glare and light trespass, less restful sleep, and disturbed nocturnal wildlife patterns. There is increasing awareness of just how much light is too much light at night. You don’t need to give in to despair over encroaching light pollution; you can join efforts to measure it, educate others, and even help stop or reduce the effects of light pollution in your community. 

Amateur astronomers and potential citizen scientists around the globe are invited to participate in the Globe at Night (GaN) program to measure light pollution. Measurements are taken by volunteers on a few scheduled days every month and submitted to their database to help create a comprehensive map of light pollution and its change over time. GaN volunteers can take and submit measurements using multiple methods ranging from low-tech naked-eye observations to high-tech sensors and smartphone apps.

Globe at Night citizen scientists can use the following methods to measure light pollution and submit their results:

• Their own smartphone camera and dedicated app
• Manually measure light pollution using their own eyes and detailed charts of the constellations
• A dedicated light pollution measurement device called a Sky Quality Meter (SQM).
• The free GaN web app from any internet-connected device (which can also be used to submit their measurements from an SQM or printed-out star charts)

Night Sky Network members joined a telecon with Connie Walker of Globe at Night in 2014 and had a lively discussion about the program’s history and how they can participate. The audio of the telecon, transcript, and links to additional resources can be found on their dedicated resource page.

DarkSky International has long been a champion in the fight against light pollution and a proponent of smart lighting design and policy. Their website (at darksky.org)  provides many resources for amateur astronomers and other like-minded people to help communities understand the negative impacts of light pollution and how smart lighting policies can not only help bring the stars back to their night skies but make their streets safer by using smarter lighting with less glare. Communities and individuals find that their nighttime lighting choices can help save considerable sums of money when they decide to light their streets and homes “smarter, not brighter” with shielded, directional lighting, motion detectors, timers, and even choosing the proper “temperature” of new LED light replacements to avoid the harsh “pure white” glare that many new streetlamps possess. Their pages on community advocacy and on how to choose dark-sky-friendly lighting are extremely helpful and full of great information. There are even local chapters of the IDA in many communities made up of passionate advocates of dark skies.

DarkSky International has notably helped usher in “Dark Sky Places“, areas around the world that are protected from light pollution. “Dark Sky Parks“, in particular, provide visitors with incredible views of the Milky Way and are perfect places to spot the wonders of a meteor shower. These parks also perform a very important function, showing the public the wonders of a truly dark sky to many people who may have never before even seen a handful of stars in the sky, let alone the full, glorious spread of the Milky Way. 

More research into the negative effects of light pollution on the health of humans and the environment is being conducted than ever before. Watching the nighttime light slowly increase in your neighborhood, combined with reading so much bad news, can indeed be disheartening! However, as awareness of light pollution and its negative effects increases, more people are becoming aware of the problem and want to be part of the solution. There is even an episode of PBS Kid’s SciGirls where the main characters help mitigate light pollution in their neighborhood!

Astronomy clubs are uniquely situated to help spread awareness of good lighting practices in their local communities in order to help mitigate light pollution. Take inspiration from Tucson, Arizona, and other dark sky-friendly communities that have adopted good lighting practices. Tucson even reduced its skyglow by 7% after its own citywide lighting conversion, proof that communities can bring the stars back with smart lighting choices.

Originally posted by Dave Prosper: November 2018
Last Updated by Kat Troche: January 2025

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