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By NASA
5 Min Read Planetary Alignments and Planet Parades
A sky chart showing Mars, Jupiter, Saturn, and Venus in a “planet parade.” Credits:
NASA/JPL-Caltech On most nights, weather permitting, you can spot at least one bright planet in the night sky. While two or three planets are commonly visible in the hours around sunset, occasionally four or five bright planets can be seen simultaneously with the naked eye. These events, often called “planet parades” or “planetary alignments,” can generate significant public interest. Though not exceedingly rare, they’re worth observing since they don’t happen every year.
Why Planets Appear Along a Line in The Sky
“Planet parade” isn’t a technical term in astronomy, and “planetary alignment” can refer to several different phenomena. As the planets of our solar system orbit the Sun, they occasionally line up in space in events called oppositions and conjunctions. A planetary alignment can also refer to apparent lineups in our sky with other planets, the Moon, or bright stars.
The planets of our solar system always appear along a line on the sky. This line, referred to as the ecliptic, represents the plane in which the planets orbit, seen from our position within the plane itself. NASA/Preston Dyches When it comes to this second type of planetary alignment, it’s important to understand that planets always appear along a line or arc across the sky. This occurs because the planets orbit our Sun in a relatively flat, disc-shaped plane. From Earth, we’re looking into that solar system plane from within. We see the racetrack of the planets from the perspective of one of the racers ourselves. When viewed edge-on, this disc appears as a line, which we call the ecliptic or ecliptic plane.
So, while planet alignment itself isn’t unusual, what makes these events special is the opportunity to observe multiple planets simultaneously with the naked eye.
Will the Planets Actually be Visible?
Before preparing to observe a planet parade, we have to consider how high the planets will appear above the horizon. For most observers to see a planet with the naked eye, it needs to be at least a few degrees above the horizon, and10 degrees or higher is best. This is crucial because Earth’s atmosphere near the ground dims celestial objects as they rise or set. Even bright planets become difficult or impossible to spot when they’re too low, as their light gets scattered and absorbed on its path to your eye. Buildings, trees, and other obstructions often block the view near the horizon as well.
This visibility challenge is particularly notable after sunset or before sunrise, where the sky is still glowing. If a planet appears very low within the sunset glow, it is very difficult to observe.
The Planets You Can See, and Those You Can’t
Five planets are visible without optical aid: Mercury, Venus, Mars, Jupiter, and Saturn. Ancient civilizations recognized these worlds as bright lights that wandered across the starscape, while the background stars remained fixed in place. In fact, the word “planet” comes to us from the Greek word for “wanderer.”
The solar system includes two additional major planets, Uranus and Neptune, plus numerous dwarf planets like Pluto and Ceres. Uranus and Neptune orbit in the dim, cold depths of the outer solar system. Neptune absolutely requires a telescope to observe. While Uranus is technically bright enough to detect with good eyesight, it’s quite faint and requires dark skies and precise knowledge of its location among similarly faint stars, so a telescope is recommended. As we’ll discuss in the next section, planet parades necessarily must be observed in twilight before dawn or after sunset, and this is not a good time to try observing extremely faint objects like Uranus and Neptune.
Thus, claims about rare six- or seven-planet alignments which include Uranus and Neptune should be viewed with the understanding that these two distant planets will not be visible to the unaided eye.
What Makes Multi-Planet Lineups Special
Lineups of four or five planet naked-eye planets with optimal visibility typically occur every few years. Mars, Jupiter, and Saturn are frequently seen in the night sky, but the addition of Venus and Mercury make four- and five-planet lineups particularly noteworthy. Both orbit closer to the Sun than Earth, with smaller, faster orbits than the other planets. Venus is visible for only a couple of months at a time when it reaches its greatest separation from the Sun (called elongation), appearing just after sunset or before sunrise. Mercury, completing its orbit in just 88 days, is visible for only a couple of weeks (or even a few days) at a time just after sunset or just before sunrise.
Planet parades aren’t single-day events, as the planets move too slowly for that. Generally, multi-planet viewing opportunities last for weeks to a month or more. Even five-planet events last for several days as Mercury briefly emerges from and returns to the Sun’s glare.
In summary, while they aren’t once-in-a-lifetime events, planetary parades afford an uncommon opportunity to look up and appreciate our place in our solar system, with diverse worlds arrayed across the sky before our very eyes.
Other Planet Lineups
Other recent and near-future multi-planet viewing opportunities:
January 2016 – Four planets visible at once before sunrise Late April to Late August 2022 – Four planets visible at once before sunrise Mid-June to Early July 2022 – Five planets visible at once before sunrise January to mid-February 2025 – Four planets visible at once after sunset Late August 2025 – Four planets visible at once before sunrise Late October 2028 – Five planets visible at once before sunrise Late February 2034 – Five planets visible at once after sunset (Venus and Mercury challenging to observe) About the January/February 2025 Planet Parade
The current four-planet lineup concludes by mid-February, as Saturn sinks increasingly lower in the sky each night after sunset. By mid-to-late February, Saturn appears less than 10 degrees above the horizon as sunset fades, making it difficult to observe for most people. While Mercury briefly joins Saturn in the post-sunset glow at the end of February, both planets will be too low and faint for most observers to spot.
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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
Earth Global Precipitation Measurement (GPM) Goddard Space Flight Center Moderate Resolution Imaging Spectroradiometer (MODIS) Water & Energy Cycle Explore More
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By NASA
International teams of astronomers monitoring a supermassive black hole in the heart of a distant galaxy have detected features never seen before using data from NASA missions and other facilities. The features include the launch of a plasma jet moving at nearly one-third the speed of light and unusual, rapid X-ray fluctuations likely arising from near the very edge of the black hole.
Radio images of 1ES 1927+654 reveal emerging structures that appear to be jets of plasma erupting from both sides of the galaxy’s central black hole following a strong radio flare. The first image, taken in June 2023, shows no sign of the jet, possibly because hot gas screened it from view. Then, starting in February 2024, the features emerge and expand away from the galaxy’s center, covering a total distance of about half a light-year as measured from the center of each structure. NSF/AUI/NSF NRAO/Meyer at al. 2025 The source is 1ES 1927+654, a galaxy located about 270 million light-years away in the constellation Draco. It harbors a central black hole with a mass equivalent to about 1.4 million Suns.
“In 2018, the black hole began changing its properties right before our eyes, with a major optical, ultraviolet, and X-ray outburst,” said Eileen Meyer, an associate professor at UMBC (University of Maryland Baltimore County). “Many teams have been keeping a close eye on it ever since.”
She presented her team’s findings at the 245th meeting of the American Astronomical Society in National Harbor, Maryland. A paper led by Meyer describing the radio results was published Jan. 13 in The Astrophysical Journal Letters.
After the outburst, the black hole appeared to return to a quiet state, with a lull in activity for nearly a year. But by April 2023, a team led by Sibasish Laha at UMBC and NASA’s Goddard Space Flight Center in Greenbelt, Maryland, had noted a steady, months-long increase in low-energy X-rays in measurements by NASA’s Neil Gehrels Swift Observatory and NICER (Neutron star Interior Composition Explorer) telescope on the International Space Station. This monitoring program, which also includes observations from NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) and ESA’s (European Space Agency) XMM-Newton mission, continues.
The increase in X-rays triggered the UMBC team to make new radio observations, which indicated a strong and highly unusual radio flare was underway. The scientists then began intensive observations using the NRAO’s (National Radio Astronomy Observatory) VLBA (Very Long Baseline Array) and other facilities. The VLBA, a network of radio telescopes spread across the U.S., combines signals from individual dishes to create what amounts to a powerful, high-resolution radio camera. This allows the VLBA to detect features less than a light-year across at 1ES 1927+654’s distance.
Active galaxy 1ES 1927+654, circled, has exhibited extraordinary changes since 2018, when a major outburst occurred in visible, ultraviolet, and X-ray light. The galaxy harbors a central black hole weighing about 1.4 million solar masses and is located 270 million light-years away. Pan-STARRS Radio data from February, April, and May 2024 reveals what appear to be jets of ionized gas, or plasma, extending from either side of the black hole, with a total size of about half a light-year. Astronomers have long puzzled over why only a fraction of monster black holes produce powerful plasma jets, and these observations may provide critical clues.
“The launch of a black hole jet has never been observed before in real time,” Meyer noted. “We think the outflow began earlier, when the X-rays increased prior to the radio flare, and the jet was screened from our view by hot gas until it broke out early last year.”
A paper exploring that possibility, led by Laha, is under review at The Astrophysical Journal. Both Meyer and Megan Masterson, a doctoral candidate at the Massachusetts Institute of Technology in Cambridge who also presented at the meeting, are co-authors.
Using XMM-Newton observations, Masterson found that the black hole exhibited extremely rapid X-ray variations between July 2022 and March 2024. During this period, the X-ray brightness repeatedly rose and fell by 10% every few minutes. Such changes, called millihertz quasiperiodic oscillations, are difficult to detect around supermassive black holes and have been observed in only a handful of systems to date.
“One way to produce these oscillations is with an object orbiting within the black hole’s accretion disk. In this scenario, each rise and fall of the X-rays represents one orbital cycle,” Masterson said.
If the fluctuations were caused by an orbiting mass, then the period would shorten as the object fell ever closer to the black hole’s event horizon, the point of no return. Orbiting masses generate ripples in space-time called gravitational waves. These waves drain away orbital energy, bringing the object closer to the black hole, increasing its speed, and shortening its orbital period.
Over two years, the fluctuation period dropped from 18 minutes to just 7 — the first-ever measurement of its kind around a supermassive black hole. If this represented an orbiting object, it was now moving at half the speed of light. Then something unexpected happened — the fluctuation period stabilized.
In this artist’s concept, matter is stripped from a white dwarf (sphere at lower right) orbiting within the innermost accretion disk surrounding 1ES 1927+654’s supermassive black hole. Astronomers developed this scenario to explain the evolution of rapid X-ray oscillations detected by ESA’s (European Space Agency) XMM-Newton satellite. ESA’s LISA (Laser Interferometer Space Antenna) mission, due to launch in the next decade, should be able to confirm the presence of an orbiting white dwarf by detecting the gravitational waves it produces. NASA/Aurore Simonnet, Sonoma State University “We were shocked by this at first,” Masterson explained. “But we realized that as the object moved closer to the black hole, its strong gravitational pull could begin to strip matter from the companion. This mass loss could offset the energy removed by gravitational waves, halting the companion’s inward motion.”
So what could this companion be? A small black hole would plunge straight in, and a normal star would quickly be torn apart by the tidal forces near the monster black hole. But the team found that a low-mass white dwarf — a stellar remnant about as large as Earth — could remain intact close to the black hole’s event horizon while shedding some of its matter. A paper led by Masterson summarizing these results will appear in the Feb. 13 edition of the journal Nature.
This model makes a key prediction, Masterson notes. If the black hole does have a white dwarf companion, the gravitational waves it produces will be detectable by LISA (Laser Interferometer Space Antenna), an ESA mission in partnership with NASA that is expected to launch in the next decade.
Download high-resolution images from NASA’s Scientific Visualization Studio
By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Media Contacts:
Claire Andreoli
301-286-1940
claire.andreoli@nasa.gov
NASA’s Goddard Space Flight Center, Greenbelt, Md.
Jill Malusky
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National Radio Astronomy Observatory, Charlottesville, Va.
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Last Updated Jan 13, 2025 Related Terms
Active Galaxies Astrophysics Black Holes Galaxies, Stars, & Black Holes Goddard Space Flight Center Jet Propulsion Laboratory Neil Gehrels Swift Observatory NICER (Neutron star Interior Composition Explorer) NuSTAR (Nuclear Spectroscopic Telescope Array) Radio Astronomy Supermassive Black Holes The Universe White Dwarfs X-ray Astronomy XMM-Newton (X-ray Multi-Mirror Newton) View the full article
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By NASA
A collage of artist concepts highlighting the novel approaches proposed by the 2025 NIAC awardees for possible future missions.Credit: NASA/Left to Right: Saurabh Vilekar, Marco Quadrelli, Selim Shahriar, Gyula Greschik, Martin Bermudez, Ryan Weed, Ben Hockman, Robert Hinshaw, Christine Gregg, Ryan Benson, Michael Hecht NASA selected 15 visionary ideas for its NIAC (NASA Innovative Advanced Concepts) program which develops concepts to transform future missions for the benefit of all. Chosen from companies and institutions across the United States, the 2025 Phase I awardees represent a wide range of aerospace concepts.
The NIAC program nurtures innovation by funding early-stage technology concept studies for future consideration and potential commercialization. The combined award for the 2025 concepts is a maximum of $2.625M in grants to evaluate technologies that could enable future aerospace missions.
“Our next steps and giant leaps rely on innovation, and the concepts born from NIAC can radically change how we explore deep space, work in low Earth orbit, and protect our home planet” said Clayton Turner, associate administrator for NASA’s Space Technology Mission Directorate in Washington. “From developing small robots that could swim through the oceans of other worlds to growing space habitats from fungi, this program continues to change the possible.”
The newly selected concepts include feasibility studies to explore the Sun’s influence on our solar system, build sustainable lunar habitats from glass, explore Saturn’s icy moon, and more. All NIAC studies are in the early stages of conceptual development and are not considered official NASA missions.
Ryan Weed, Helicity Space LLC in Pasadena, California, proposes a constellation of spacecraft powered by the Helicity Drive, a compact and scalable fusion propulsion system, that could enable rapid, multi-directional exploration of the heliosphere and beyond, providing unprecedented insights on how the Sun interacts with our solar system and interstellar space. Demonstrating the feasibility of fusion propulsion could also benefit deep space exploration including crewed missions to Mars.
Martin Bermudez, Skyeports LLC in Sacramento, California, presents the concept of constructing a large-scale, lunar glass habitat in a low-gravity environment. Nicknamed LUNGS (Lunar Glass Structure), this approach involves melting lunar glass compounds to create a large spherical shell structure. This idea offers a promising solution for establishing self-sustaining, large-scale habitats on the lunar surface.
Justin Yim, University of Illinois in Urbana, proposes a jumping robot appropriately named LEAP (Legged Exploration Across the Plume), as a novel robotic sampling concept to explore Enceladus, a small, icy moon of Saturn that’s covered in geysers, or jets. The LEAP robots could enable collection of pristine, ocean-derived material directly from Enceladus’s jets and measurement of particle properties across multiple jets by traveling from one to another.
“All advancements begin as an idea. The NIAC program allows NASA to invest in unique ideas enabling innovation and supporting the nation’s aerospace economy,” said John Nelson, program executive for NASA’s Innovative Advanced Concepts in Washington.
The NIAC researchers, known as fellows, will investigate the fundamental premise of their concepts, identify potential challenges, and look for opportunities to bring these concepts to life.
In addition to the projects mentioned above, the following selectees received 2025 NIAC Phase I grants:
Michael Hecht, Massachusetts Institute of Technology, Cambridge: EVE (Exploring Venus with Electrolysis) Selim Shahriar, Northwestern University, Evanston, Illinois: SUPREME-QG: Space-borne Ultra-Precise Measurement of the Equivalence Principle Signature of Quantum Gravity Phillip Ansell, University of Illinois, Urbana: Hy2PASS (Hydrogen Hybrid Power for Aviation Sustainable Systems) Ryan Benson, ThinkOrbital Inc., Boulder, Colorado: Construction Assembly Destination Gyula Greschik, Tentguild Engineering Co, Boulder, Colorado: The Ribbon: Structure Free Sail for Solar Polar Observation Marco Quadrelli, NASA’s Jet Propulsion Laboratory in California’s Silicon Valley: PULSAR: Planetary pULSe-tAkeRv Ben Hockman, NASA’s Jet Propulsion Laboratory in California’s Silicon Valley: TOBIAS: Tethered Observatory for Balloon-based Imaging and Atmospheric Sampling Kimberly Weaver, NASA’s Goddard Space Flight Center in Greenbelt, Maryland: Beholding Black Hole Power with the Accretion Explorer Interferometer John Mather NASA’s Goddard Space Flight Center in Greenbelt, Maryland: Inflatable Starshade for Earthlike Exoplanets Robert Hinshaw, NASA’s Ames Research Center in Moffett Field, California: MitoMars: Targeted Mitochondria Replacement Therapy to Boost Deep Space Endurance Christine Gregg, NASA’s Ames Research Center in Moffett Field, California: Dynamically Stable Large Space Structures via Architected Metamaterials Saurabh Vilekar, Precision Combustion, North Haven, Connecticut: Thermo-Photo-Catalysis of Water for Crewed Mars Transit Spacecraft Oxygen Supply NASA’s Space Technology Mission Directorate funds the NIAC program, as it is responsible for developing the agency’s new cross-cutting technologies and capabilities to achieve its current and future missions.
To learn more about NIAC, visit:
https://www.nasa.gov/niac
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Jasmine Hopkins
Headquarters, Washington
321-431-4624
jasmine.s.hopkins@nasa.gov
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Last Updated Jan 10, 2025 EditorJessica TaveauLocationNASA Headquarters Related Terms
NASA Innovative Advanced Concepts (NIAC) Program Space Technology Mission Directorate View the full article
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By NASA
NASA’s 2024 AI Use Case inventory highlights the agency’s commitment to integrating artificial intelligence in its space missions and operations. The agency’s updated inventory consists of active AI use cases, ranging from AI-driven autonomous space operations, such as navigation for the Perseverance Rover on Mars, to advanced data analysis for scientific discovery.
AI Across NASA
NASA’s use of AI is diverse and spans several key areas of its missions:
Autonomous Exploration and Navigation
AEGIS (Autonomous Exploration for Gathering Increased Science): AI-powered system designed to autonomously collect scientific data during planetary exploration. Enhanced AutoNav for Perseverance Rover: Utilizes advanced autonomous navigation for Mars exploration, enabling real-time decision-making. MLNav (Machine Learning Navigation): AI-driven navigation tools to enhance movement across challenging terrains. Perseverance Rover on Mars – Terrain Relative Navigation: AI technology supporting the rover’s navigation across Mars, improving accuracy in unfamiliar terrain. Mission Planning and Management
ASPEN Mission Planner: AI-assisted tool that helps streamline space mission planning and scheduling, optimizing mission efficiency. AWARE (Autonomous Waiting Room Evaluation): AI system that manages operational delays, improving mission scheduling and resource allocation. CLASP (Coverage Planning & Scheduling): AI tools for resource allocation and scheduling, ensuring mission activities are executed seamlessly. Onboard Planner for Mars2020 Rover: AI system that helps the Perseverance Rover autonomously plan and schedule its tasks during its mission. Environmental Monitoring and Analysis
SensorWeb for Environmental Monitoring: AI-powered system used to monitor environmental factors such as volcanoes, floods, and wildfires on Earth and beyond. Volcano SensorWeb: Similar to SensorWeb, but specifically focused on volcanic activity, leveraging AI to enhance monitoring efforts. Global, Seasonal Mars Frost Maps: AI-generated maps to study seasonal variations in Mars’ atmosphere and surface conditions. Data Management and Automation
NASA OCIO STI Concept Tagging Service: AI tools that organize and tag NASA’s scientific data, making it easier to access and analyze. Purchase Card Management System (PCMS): AI-assisted system for streamlining NASA’s procurement processes and improving financial operations. Aerospace and Air Traffic Control
NextGen Methods for Air Traffic Control: AI tools to optimize air traffic control systems, enhancing efficiency and reducing operational costs. NextGen Data Analytics: Letters of Agreement: AI-driven analysis of agreements within air traffic control systems, improving management and operational decision-making. Space Exploration
Mars2020 Rover (Perseverance): AI systems embedded within the Perseverance Rover to support its mission to explore Mars. SPOC (Soil Property and Object Classification): AI-based classification system used to analyze soil and environmental features, particularly for Mars exploration. Ethical AI: NASA’s Responsible Approach
NASA ensures that all AI applications adhere to Responsible AI (RAI) principles outlined by the White House in its Executive Order 13960. This includes ensuring AI systems are transparent, accountable, and ethical. The agency integrates these principles into every phase of development and deployment, ensuring AI technologies used in space exploration are both safe and effective.
Looking Forward: AI’s Expanding Role
As AI technologies evolve, NASA’s portfolio of AI use cases will continue to grow. With cutting-edge tools currently in development, the agency is poised to further integrate AI into more aspects of space exploration, from deep space missions to sustainable solutions for planetary exploration.
By maintaining a strong commitment to both technological innovation and ethical responsibility, NASA is not only advancing space exploration but also setting an industry standard for the responsible use of artificial intelligence in scientific and space-related endeavors.
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