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Large Solar Eruption As Filament Breaks Loose
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By European Space Agency
Thanks to its newly tilted orbit around the Sun, the European Space Agency-led Solar Orbiter spacecraft is the first to image the Sun’s poles from outside the ecliptic plane. Solar Orbiter’s unique viewing angle will change our understanding of the Sun’s magnetic field, the solar cycle and the workings of space weather.
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By NASA
2 Min Read June’s Night Sky Notes: Seasons of the Solar System
Two views of the planet Uranus appear side-by-side for comparison. At the top, left corner of the left image is a two-line label. The top line reads Uranus November 9, 2014. The bottoms line reads HST WFC3/UVIS. At the top, left corner of the right image is the label November 9, 2022. At the left, bottom corner of each image is a small, horizontal, white line. In both panels, over this line is the value 25,400 miles. Below the line is the value 40,800 kilometers. At the top, right corner of the right image are three, colored labels representing the color filters used to make these pictures. Located on three separate lines, these are F467M in blue, F547M in green, and F485M in red. On the bottom, right corner of the right image are compass arrows showing north toward the top and east toward the left. Credits:
NASA by Kat Troche of the Astronomical Society of the Pacific
Here on Earth, we undergo a changing of seasons every three months. But what about the rest of the Solar System? What does a sunny day on Mars look like? How long would a winter on Neptune be? Let’s take a tour of some other planets and ask ourselves what seasons might look like there.
Martian Autumn
Although Mars and Earth have nearly identical axial tilts, a year on Mars lasts 687 Earth days (nearly 2 Earth years) due to its average distance of 142 million miles from the Sun, making it late autumn on the red planet. This distance and a thin atmosphere make it less than perfect sweater weather. A recent weather report from Gale Crater boasted a high of -18 degrees Fahrenheit for the week of May 20, 2025.
Credit: NASA/JPL-Caltech Seven Years of Summer
Saturn has a 27-degree tilt, very similar to the 25-degree tilt of Mars and the 23-degree tilt of Earth. But that is where the similarities end. With a 29-year orbit, a single season on the ringed planet lasts seven years. While we can’t experience a Saturnian season, we can observe a ring plane crossing here on Earth instead. The most recent plane crossing took place in March 2025, allowing us to see Saturn’s rings ‘disappear’ from view.
A Lifetime of Spring
NASA Hubble Space Telescope observations in August 2002 show that Neptune’s brightness has increased significantly since 1996. The rise is due to an increase in the amount of clouds observed in the planet’s southern hemisphere. These increases may be due to seasonal changes caused by a variation in solar heating. Because Neptune’s rotation axis is inclined 29 degrees to its orbital plane, it is subject to seasonal solar heating during its 164.8-year orbit of the Sun. This seasonal variation is 900 times smaller than experienced by Earth because Neptune is much farther from the Sun. The rate of seasonal change also is much slower because Neptune takes 165 years to orbit the Sun. So, springtime in the southern hemisphere will last for several decades! Remarkably, this is evidence that Neptune is responding to the weak radiation from the Sun. These images were taken in visible and near-infrared light by Hubble’s Wide Field and Planetary Camera 2. Credit: NASA, L. Sromovsky, and P. Fry (University of Wisconsin-Madison) Even further away from the Sun, each season on Neptune lasts over 40 years. Although changes are slower and less dramatic than on Earth, scientists have observed seasonal activity in Neptune’s atmosphere. These images were taken between 1996 and 2002 with the Hubble Space Telescope, with brightness in the southern hemisphere indicating seasonal change.
As we welcome summer here on Earth, you can build a Suntrack model that helps demonstrate the path the Sun takes through the sky during the seasons. You can find even more fun activities and resources like this model on NASA’s Wavelength and Energy activity.
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By NASA
2 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
Artist concept highlighting the novel approach proposed by the 2025 NIAC awarded selection of Gravity Poppers: Hopping Probes for the Interior Mapping of Small Solar System Bodies concept.NASA/Benjamin Hockman Benjamin Hockman
NASA Jet Propulsion Laboratory
The goal of this effort is to develop a robust and affordable mission architecture that enables the gravimetric density reconstruction of small body interiors to unprecedented precision. Our architecture relies on the novel concept of “Gravity Poppers,” which are small, minimalistic probes that are deployed to the surface of a small body and periodically “pop” so as to perpetuate a random hopping motion around the body. By tracking a large swarm of poppers from orbit, a mother spacecraft can precisely estimate their trajectories and continuously refine a high-resolution map of the body’s gravity field, and thus, its internal mass distribution. Hopping probes are also equipped with minimalistic in-situ sensors to measure the surface temperature (when landed) and strength (when bouncing) in order to complement the gravity field and build a more accurate picture of the interior. The Phase I study focused on feasibility assessment of three core technologies that enable such a mission: (1) the mechanical design of hopping probes to be small, simple, robust, and “visible” to a distant spacecraft, (2) the tracking strategy for detecting and estimating the trajectories of a large number of ballistic probes, and (3) the algorithmic framework by which such measurements can be used to iteratively refine a gravity model of the body. The key finding was that the concept is feasible, and demonstrated to have the potential to resolve extremely accurate gravity models, allowing scientists to localize density anomalies such as “weighing” large boulders on the surface. This Phase II Proposal aims to further develop these three core technologies through continued mission trade studies and sensitivity analysis, case studies for simulated missions, and hardware prototypes demonstrating both hopping behavior and tracking performance.
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Last Updated May 27, 2025 EditorLoura Hall Related Terms
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By NASA
6 min read
Preparations for Next Moonwalk Simulations Underway (and Underwater)
The SWOT satellite is helping scientists size up flood waves on waterways like the Yellowstone River, pictured here in October 2024 in Montana. SWOT measures the height of surface waters, including the ocean, and hundreds of thousands of rivers, lakes, and reservoirs in the U.S. alone.NPS In a first, researchers from NASA and Virginia Tech used satellite data to measure the height and speed of potentially hazardous flood waves traveling down U.S. rivers. The three waves they tracked were likely caused by extreme rainfall and by a loosened ice jam. While there is currently no database that compiles satellite data on river flood waves, the new study highlights the potential of space-based observations to aid hydrologists and engineers, especially those working in communities along river networks with limited flood control structures such as levees and flood gates.
Unlike ocean waves, which are ordinarily driven by wind and tides, and roll to shore at a steady clip, river waves (also called flood or flow waves) are temporary surges stretching tens to hundreds of miles. Typically caused by rainfall or seasonal snowmelt, they are essential to shuttling nutrients and organisms down a river. But they can also pose hazards: Extreme river waves triggered by a prolonged downpour or dam break can produce floods.
“Ocean waves are well known from surfing and sailing, but rivers are the arteries of the planet. We want to understand their dynamics,” said Cedric David, a hydrologist at NASA’s Jet Propulsion Laboratory in Southern California and a coauthor of a new study published May 14 in Geophysical Research Letters.
SWOT is depicted in orbit in this artist’s concept, with sunlight glinting off one of its solar panels and both antennas of its key instrument — the Ka-band Radar Interferometer (KaRIn) — extended. The antennas collect data along a swath 30 miles (50 kilometers) wide on either side of the satellite.CNES Measuring Speed and Size
To search for river waves for her doctoral research, lead author Hana Thurman of Virginia Tech turned to a spacecraft launched in 2022. The SWOT (Surface Water and Ocean Topography) satellite is a collaboration between NASA and the French space agency CNES (Centre National d’Études Spatiales). It is surveying the height of nearly all of Earth’s surface waters, both fresh and salty, using its sensitive Ka-band Radar Interferometer (KaRIn). The instrument maps the elevation and width of water bodies by bouncing microwaves off the surface and timing how long the signal takes to return.
“In addition to monitoring total storage of waters in lakes and rivers, we zoom in on dynamics and impacts of water movement and change,” said Nadya Vinogradova Shiffer, SWOT program scientist at NASA Headquarters in Washington.
Thurman knew that SWOT has helped scientists track rising sea levels near the coast, spot tsunami slosh, and map the seafloor, but could she identify river height anomalies in the data indicating a wave on the move?
She found that the mission had caught three clear examples of river waves, including one that arose abruptly on the Yellowstone River in Montana in April 2023. As the satellite passed overhead, it observed a 9.1-foot-tall (2.8-meter-tall) crest flowing toward the Missouri River in North Dakota. It was divided into a dramatic 6.8-mile-long (11-kilometer-long) peak followed by a more drawn‐out tail. These details are exciting to see from orbit and illustrate the KaRIn instrument’s uniquely high spatial resolution, Thurman said.
Sleuthing through optical Sentinel-2 imagery of the area, she determined that the wave likely resulted from an ice jam breaking apart upstream and releasing pent-up water.
The other two river waves that Thurman and the team found were triggered by rainfall runoff. One, spotted by SWOT starting on Jan. 25, 2024, on the Colorado River south of Austin, Texas, was associated with the largest flood of the year on that section of river. Measuring over 30 feet (9 meters) tall and 166 miles (267 kilometers) long, it traveled around 3.5 feet (1.07 meters) per second for over 250 miles (400 kilometers) before discharging into Matagorda Bay.
The other wave originated on the Ocmulgee River near Macon, Georgia, in March 2024. Measuring over 20 feet (6 meters) tall and extending more than 100 miles (165 kilometers), it traveled about a foot (0.33 meters) per second for more than 124 miles (200 kilometers).
“We’re learning more about the shape and speed of flow waves, and how they change along long stretches of river,” Thurman said. “That could help us answer questions like, how fast could a flood get here and is infrastructure at risk?”
Complementary Observations
Engineers and water managers measuring river waves have long relied on stream gauges, which record water height and estimate discharge at fixed points along a river. In the United States, stream gauge networks are maintained by agencies including the U.S. Geological Survey. They are sparser in other parts of the world.
“Satellite data is complementary because it can help fill in the gaps,” said study supervisor George Allen, a hydrologist and remote sensing expert at Virginia Tech.
If stream gauges are like toll booths clocking cars as they pass, SWOT is like a traffic helicopter taking snapshots of the highway.
The wave speeds that SWOT helped determine were similar to those calculated using gauge data alone, Allen said, showing how the satellite could help monitor waves in river basins without gauges. Knowing where and why river waves develop can help scientists tracking changing flood patterns around the world.
Orbiting Earth multiple times each day, SWOT is expected to observe some 55% of large-scale floods at some stage in their life cycle. “If we see something in the data, we can say something,” David said of SWOT’s potential to flag dangerous floods in the making. “For a long time, we’ve stood on the banks of our rivers, but we’ve never seen them like we are now.”
More About SWOT
The SWOT satellite was jointly developed by NASA and CNES, with contributions from the Canadian Space Agency (CSA) and the UK Space Agency. NASA’s Jet Propulsion Laboratory, managed for the agency by Caltech in Pasadena, California, leads the U.S. component of the project. For the flight system payload, NASA provided the Ka-band radar interferometer (KaRIn) instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. The Doppler Orbitography and Radioposition Integrated by Satellite system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground operations were provided by CNES. The KaRIn high-power transmitter assembly was provided by CSA.
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Jane J. Lee / Andrew Wang
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Written by Sally Younger
2025-074
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Last Updated May 21, 2025 Related Terms
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