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Astronomers Find Jupiter-like Cloud Bands on Closest Brown Dwarf
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By NASA
4 min read
May’s Night Sky Notes: How Do We Find Exoplanets?
Astronomers have been trying to discover evidence that worlds exist around stars other than our Sun since the 19th century. By the mid-1990s, technology finally caught up with the desire for discovery and led to the first discovery of a planet orbiting another sun-like star, Pegasi 51b. Why did it take so long to discover these distant worlds, and what techniques do astronomers use to find them?
The Transit Method
A planet passing in front of its parent star creates a drop in the star’s apparent brightness, called a transit. Exoplanet Watch participants can look for transits in data from ground-based telescopes, helping scientists refine measurements of the length of a planet’s orbit around its star. Credit: NASA’s Ames Research Center One of the most famous exoplanet detection methods is the transit method, used by Kepler and other observatories. When a planet crosses in front of its host star, the light from the star dips slightly in brightness. Scientists can confirm a planet orbits its host star by repeatedly detecting these incredibly tiny dips in brightness using sensitive instruments. If you can imagine trying to detect the dip in light from a massive searchlight when an ant crosses in front of it, at a distance of tens of miles away, you can begin to see how difficult it can be to spot a planet from light-years away! Another drawback to the transit method is that the distant solar system must be at a favorable angle to our point of view here on Earth – if the distant system’s angle is just slightly askew, there will be no transits. Even in our solar system, a transit is very rare. For example, there were two transits of Venus visible across our Sun from Earth in this century. But the next time Venus transits the Sun as seen from Earth will be in the year 2117 – more than a century from the 2012 transit, even though Venus will have completed nearly 150 orbits around the Sun by then!
The Wobble Method
As a planet orbits a star, the star wobbles. This causes a change in the appearance of the star’s spectrum called Doppler shift. Because the change in wavelength is directly related to relative speed, astronomers can use Doppler shift to calculate exactly how fast an object is moving toward or away from us. Astronomers can also track the Doppler shift of a star over time to estimate the mass of the planet orbiting it. NASA, ESA, CSA, Leah Hustak (STScI) Spotting the Doppler shift of a star’s spectra was used to find Pegasi 51b, the first planet detected around a Sun-like star. This technique is called the radial velocity or “wobble” method. Astronomers split up the visible light emitted by a star into a rainbow. These spectra, and gaps between the normally smooth bands of light, help determine the elements that make up the star. However, if there is a planet orbiting the star, it causes the star to wobble ever so slightly back and forth. This will, in turn, cause the lines within the spectra to shift ever so slightly towards the blue and red ends of the spectrum as the star wobbles slightly away and towards us. This is caused by the blue and red shifts of the star’s light. By carefully measuring the amount of shift in the star’s spectra, astronomers can determine the size of the object pulling on the host star and if the companion is indeed a planet. By tracking the variation in this periodic shift of the spectra, they can also determine the time it takes the planet to orbit its parent star.
Direct Imaging
Finally, exoplanets can be revealed by directly imaging them, such as this image of four planets found orbiting the star HR 8799! Space telescopes use instruments called coronagraphs to block the bright light from the host star and capture the dim light from planets. The Hubble Space Telescope has captured images of giant planets orbiting a few nearby systems, and the James Webb Space Telescope has only improved on these observations by uncovering more details, such as the colors and spectra of exoplanet atmospheres, temperatures, detecting potential exomoons, and even scanning atmospheres for potential biosignatures!
NASA’s James Webb Space Telescope has provided the clearest look in the infrared yet at the iconic multi-planet system HR 8799. The closest planet to the star, HR 8799 e, orbits 1.5 billion miles from its star, which in our solar system would be located between the orbit of Saturn and Neptune. The furthest, HR 8799 b, orbits around 6.3 billion miles from the star, more than twice Neptune’s orbital distance. Colors are applied to filters from Webb’s NIRCam (Near-Infrared Camera), revealing their intrinsic differences. A star symbol marks the location of the host star HR 8799, whose light has been blocked by the coronagraph. In this image, the color blue is assigned to 4.1 micron light, green to 4.3 micron light, and red to the 4.6 micron light. NASA, ESA, CSA, STScI, W. Balmer (JHU), L. Pueyo (STScI), M. Perrin (STScI) You can find more information and activities on NASA’s Exoplanets page, such as the Eyes on Exoplanets browser-based program, The Exoplaneteers, and some of the latest exoplanet news. Lastly, you can find more resources in our News & Resources section, including a clever demo on how astronomers use the wobble method to detect planets!
The future of exoplanet discovery is only just beginning, promising rich rewards in humanity’s understanding of our place in the Universe, where we are from, and if there is life elsewhere in our cosmos.
Originally posted by Dave Prosper: July 2015
Last Updated by Kat Troche: April 2025
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By European Space Agency
Each year, cutting-edge technologies developed by the European Space Agency (ESA) for its complex missions and scientific discoveries find new life in applications used to benefit Earth and improve our daily lives.
From 9–13 April, ESA was guest of honour at the 50th International Exhibition of Inventions Geneva in Switzerland with more than 1000 inventions, which attracted 30 000 visitors from the public. ESA showcased its new technologies and applications that have been invented for space missions and patented for use in and outside the space arena.
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By NASA
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The Double Asteroid Redirection Test required extreme precision in mission planning to achieve its mission of impacting an asteroid. The founders of Continuum Space worked on astrodynamics relating to this mission, which they used to inform their product.NASA Planning space missions is a very involved process, ensuring orbits are lined up and spacecraft have enough fuel is imperative to the long-term survival of orbital assets. Continuum Space Systems Inc. of Pasadena, California, produces a cloud-based platform that gives mission planners everything they need to certify that their space resources can accomplish their goals.
Continuum’s story begins at NASA’s Jet Propulsion Laboratory in Southern California. Loic Chappaz, the company’s co-founder, started at JPL as an intern working on astrodynamics related to NASA’s Double Asteroid Redirection Test. There he met Leon Alkalai, a JPL technical fellow who spent his 30-year career at the center planning deep space missions. After Alkalai retired from NASA, he founded Mandala Space Ventures, a startup that explored several avenues of commercial space development. Chappaz soon became Mandala’s first employee, but to plan their future, Mandala’s leadership began thinking about the act of planning itself.
Because the staff had decades of combined experience at JPL, they knew the center had the building blocks for the software they needed. After licensing several pieces of software from JPL, the company began building planning systems that were highly adaptable to any space mission they could come up with. Mandala eventually evolved into a venture firm that incubated space-related startups. However, because Mandala had invested considerably in developing mission-planning tools, further development could be performed by a new company, and Continuum was fully spun off from Mandala in 2021.
Continuum’s platform includes several features for mission planners, such as plotting orbital maneuvers and risk management evaluations. Some of these are built upon software licensed from the Jet Propulsion Laboratory.Continuum Space Systems Inc. Continuum’s tools are designed to take a space mission from concept to completion. There are three different components to their “mission in a box” — design, build and test, and mission operations. The base of these tools are several pieces of software developed at NASA. As of 2024, several space startups have begun planning missions with Continuum’s NASA-inspired software, as well as established operators of satellite constellations. From Continuum to several startups, NASA technologies continue to prove a valuable foundation for the nation’s space economy.
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Last Updated Mar 25, 2025 Related Terms
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By NASA
3 min read
NASA’s Cloud-based Confluence Software Helps Hydrologists Study Rivers on a Global Scale
The Paraná River in northern Argentina. Confluence, which is open-source and free to use, allows researchers to estimate river discharge and suspended sediment levels in Earth’s rivers at a global scale. NASA/ISS Rivers and streams wrap around Earth in complex networks millions of miles long, driving trade, nurturing ecosystems, and stocking critical reserves of freshwater.
But the hydrologists who dedicate their professional lives to studying this immense web of waterways do so with a relatively limited set of tools. Around the world, a patchwork of just 3,000 or so river gauge stations supply regular, reliable data, making it difficult for hydrologists to detect global trends.
“The best way to study a river,” said Colin Gleason, Armstrong Professional Development Professor of Civil and Environmental Engineering at the University of Massachusetts, Amherst, “is to get your feet wet and visit it yourself. The second best way to study a river is to use a river gauge.”
Now, thanks to Gleason and a team of more than 30 researchers, there’s another option: ‘Confluence,’ an analytic collaborative framework that leverages data from NASA’s Surface Water and Ocean Topography (SWOT) mission and the Harmonized Landsat Sentinel-2 archive (HLS) to estimate river discharge and suspended sediment levels in every river on Earth wider than 50 meters. NASA’s Physical Oceanography Distributed Active Archive Center (PO.DAAC) hosts the software, making it open-source and free for users around the world.
By incorporating both altimetry data from SWOT which informs discharge estimates, and optical data from HLS, which informs estimates of suspended sediment data, Confluence marks the first time hydrologists can create timely models of river size and water quality at a global scale. Compared to existing workflows for estimating suspended sediment using HLS data, Confluence is faster by a factor of 30.
I can’t do global satellite hydrology without this system. Or, I could, but it would be extremely time consuming and expensive.
Colin Gleason
Nikki Tebaldi, a Cloud Adoption Engineer at NASA’s Jet Propulsion Laboratory (JPL) and Co-Investigator for Confluence, was the lead developer on this project. She said that while the individual components of Confluence have been around for decades, bringing them together within a single, cloud-based processing pipeline was a significant challenge.
“I’m really proud that we’ve pieced together all of these different algorithms, got them into the cloud, and we have them all executing commands and working,” said Tebaldi.
Suresh Vannan, former manager of PO.DAAC and a Co-Investigator for Confluence, said this new ability to produce timely, global estimates of river discharge and quality will have a huge impact on hydrological models assessing everything from the health of river ecosystems to snowmelt.
“There are a bunch of science applications that river discharge can be used for, because it’s pretty much taking a snapshot of what the river looks like, how it behaves. Producing that snapshot on a global scale is a game changer,” said Vannan.
While the Confluence team is still working with PO.DAAC to complete their software package, users can currently access the Confluence source code here. For tutorials, manuals, and other user guides, visit the PO.DAAC webpage here.
All of these improvements to the original Confluence algorithms developed for SWOT were made possible by NASA’s Advanced Intelligent Systems Technology (AIST) program, a part of the agency’s Earth Science Technology Office (ESTO), in collaboration with SWOT and PO.DAAC.
To learn more about opportunities to develop next-generation technologies for studying Earth from outer space, visit ESTO’s solicitation page here.
Project Lead: Colin Gleason / University of Massachusetts, Amherst
Sponsoring Organization: Advanced Intelligent Systems Technology program, within NASA’s Earth Science Technology Office
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Last Updated Feb 04, 2025 Related Terms
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By NASA
3 Min Read NASA Scientists Find New Human-Caused Shifts in Global Water Cycle
Cracked mud and salt on the valley floor in Death Valley National Park in California can become a reflective pool after rains. (File photo) Credits: NPS/Kurt Moses In a recently published paper, NASA scientists use nearly 20 years of observations to show that the global water cycle is shifting in unprecedented ways. The majority of those shifts are driven by activities such as agriculture and could have impacts on ecosystems and water management, especially in certain regions.
“We established with data assimilation that human intervention in the global water cycle is more significant than we thought,” said Sujay Kumar, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and a co-author of the paper published in the Proceedings of the National Academy of Sciences.
The shifts have implications for people all over the world. Water management practices, such as designing infrastructure for floods or developing drought indicators for early warning systems, are often based on assumptions that the water cycle fluctuates only within a certain range, said Wanshu Nie, a research scientist at NASA Goddard and lead author of the paper.
“This may no longer hold true for some regions,” Nie said. “We hope that this research will serve as a guide map for improving how we assess water resources variability and plan for sustainable resource management, especially in areas where these changes are most significant.”
One example of the human impacts on the water cycle is in North China, which is experiencing an ongoing drought. But vegetation in many areas continues to thrive, partially because producers continue to irrigate their land by pumping more water from groundwater storage, Kumar said. Such interrelated human interventions often lead to complex effects on other water cycle variables, such as evapotranspiration and runoff.
Nie and her colleagues focused on three different kinds of shifts or changes in the cycle: first, a trend, such as a decrease in water in a groundwater reservoir; second, a shift in seasonality, like the typical growing season starting earlier in the year, or an earlier snowmelt; and third a change in extreme events, like “100-year floods” happening more frequently.
The scientists gathered remote sensing data from 2003 to 2020 from several different NASA satellite sources: the Global Precipitation Measurement mission satellite for precipitation data, a soil moisture dataset from the European Space Agency’s Climate Change Initiative, and the Gravity Recovery and Climate Experiment satellites for terrestrial water storage data. They also used products from the Moderate Resolution Imaging Spectroradiometer satellite instrument to provide information on vegetation health.
“This paper combines several years of our team’s effort in developing capabilities on satellite data analysis, allowing us to precisely simulate continental water fluxes and storages across the planet,” said Augusto Getirana, a research scientist at NASA Goddard and a co-author of the paper.
The study results suggest that Earth system models used to simulate the future global water cycle should evolve to integrate the ongoing effects of human activities. With more data and improved models, producers and water resource managers could understand and effectively plan for what the “new normal” of their local water situation looks like, Nie said.
By Erica McNamee
NASA’s Goddard Space Flight Center, Greenbelt, Maryland
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Last Updated Jan 16, 2025 EditorKate D. RamsayerContactKate D. Ramsayerkate.d.ramsayer@nasa.gov Related Terms
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