SPACE/COSMOS
Space storms light up Japan’s sky
Faint red auroras seen over Japan could be hiding space storms that are stronger than previously thought
image:
Low-latitude aurora observed on 28 June 2024 in Yoichi, Hokkaido, Japan.
view moreCredit: Tomohiro M. Nakayama
On a special night if you are lucky you might catch a faint red glow quietly lighting up Japan’s sky, stretching low along the horizon and easy to miss if you are not looking carefully. Subtle and diffuse, it probably appears as a soft crimson haze. But behind this glowing beauty are countless charged particles traveling from the Sun toward Earth’s magnetic field, which then collide with oxygen atoms high above our planet. At these great heights, where the air is extremely thin, the excited oxygen atoms then release their energy as dim red light, creating the auroras we see from the ground.
In a new study published in the Journal of Space Weather and Space Climate, researchers from Hokkaido University and the Okinawa Institute of Science and Technology observed red auroras over Japan that stretched to unexpectedly high altitudes, about 500 to 800 kilometers above Earth.
Every now and then, a magnetic storm occurs, during which charged particles from the Sun disturb Earth’s magnetic field, producing auroras. Typically, such auroras appear during a strong geomagnetic storm. However, new findings show that auroras can also occur during a moderately intense storm, challenging our understanding of how they form and how we measure the strength of space storms.
Auroras are usually seen near the poles as bright, shimmering lights produced when charged particles from the Sun collide with Earth’s atmosphere. When they appear further south, including in Japan, they are generally linked to strong geomagnetic storms and occur at lower altitudes of around 200 to 400 kilometers.
“We found that red auroras can extend to extremely high altitudes even during those storms that are measured as moderately intense. I was really surprised because I didn’t expect such tall auroras to appear even during moderately intense storms,” says Tomohiro M. Nakayama, lead author of the study. “This suggests that these storms may actually be stronger than conventional indices indicate.”
The team analyzed five auroral events observed from Hokkaido between June 2024 and March 2025. During these events, bursts of charged particles from the Sun compressed Earth’s magnetosphere—the invisible magnetic shield that surrounds the planet. Although the storms appeared moderate based on standard indices, this compression was unusually strong.
The researchers propose that such intense compression of Earth’s magnetosphere, driven by dense streams of solar wind, would have heated the upper atmosphere and lifted the region where red auroras form to much higher altitudes than usual. At the same time, the outflow of charged particles could have masked the true strength of the storms, making them appear weaker than they actually were.
To study this further, the team combined satellite data with photographs taken by citizen scientists from across Japan. By analyzing the elevation angles of the auroras in these images and tracing them along Earth’s magnetic field lines, they reconstructed how high the glowing structures extended into the sky.
Widespread participation from across Japan proved crucial here. With observers spread around the country recording the events, they could capture rare auroral occurrences from multiple locations, revealing details that traditional observation networks might miss.
These findings have important implications beyond the beauty of the night sky. When the upper atmosphere heats and expands, it increases atmospheric drag on satellites orbiting the Earth. This can alter their paths and, in some cases, cause them to lose altitude more quickly than expected.
“As the number of satellites in low Earth orbit continues to grow, understanding these effects is increasingly important,” says Nakayama. “Our results could help improve space weather forecasting and support safer satellite operations.”
Journal
Journal of Space Weather and Space Climate
Method of Research
Observational study
Subject of Research
Not applicable
Article Title
Faint red auroras as seen from Japan associated with intense magnetospheric compression
Article Publication Date
19-May-2026
Atmosphere of Saturn-sized planet with Earth-like temperature contains methane
Astronomers use NASA’s James Webb Space Telescope to determine composition of the atmosphere of a distant, temperate gas giant planet for the first time
image:
Artist's impression of a gas giant planet orbiting its distant host star. New research, led by astronomers at Penn State and the Jet Propulsion Laboratory, used NASA’s James Webb Space Telescope to analyze the atmosphere of a gas giant planet about the size of Saturn but with Earth-like temperatures and found it to be rich in methane.
view moreCredit: NASA/JPL-Caltech
UNIVERSITY PARK, Pa. — A planet that is about the size of Saturn, but with a temperature more like Earth’s, has an atmosphere rich in methane, according to a new study using NASA’s James Webb Space Telescope (JWST). Unlike the gas giant planets — Jupiter and Saturn — in Earth’s solar system, which are distant from the sun and therefore extremely cold, and so-called “hot Jupiters” — giant planets beyond the solar system that are scorching hot due to their proximity to the stars they orbit — the planet is one of only a handful of known temperate, giant planets and the first to have its atmosphere analyzed. The new details about the composition of the planet’s atmosphere will inform models of planetary formation and evolution and could improve astronomer’s understanding of how Earth’s atmosphere works, according to the research team.
A paper describing the study, by a team of researchers led by astronomers at Penn State and NASA’s Jet Propulsion Laboratory (JPL) at the California Institute of Technology, published today (May 20) in the Astronomical Journal.
“One of the main advantages of studies of planets beyond our solar system, known as exoplanets, is the ability to study many different types of planets — especially ones that we don’t see in the solar system — to learn about how planetary systems form and evolve,” said Renyu Hu, associate professor of astronomy and astrophysics in the Penn State Eberly College of Science and leader of the research team. “Since the first exoplanet was discovered in 1992 by a team that included Aleksander Wolszczan at Penn State, astronomers have found thousands of exoplanets. But only a few giant, temperate exoplanets are known and this is the first time that we have been able to study the atmosphere of one of them in detail.”
The planet, called TOI-199b, orbits a star that is more than 330 light-years from Earth about every hundred days. Its temperature is about 175 degrees Fahrenheit, which is still hot from a human perspective but not too much hotter than the highest recoded temperatures on Earth at around134 degrees and is easily reached, for example, on the dashboards of cars parked in directly sunlight. It’s significantly more temperate than the hot Jupiters that can reach 1000s of degrees and the cold solar-system gas giants that are hundreds of degrees below zero.
To characterize an exoplanet’s atmosphere, astronomers use a technique called transmission spectroscopy to analyze light from the star that passes through the planet’s atmosphere. To work, the planet’s orbit must align such that it passes between its star and the telescope. Instruments on the JWST separate the star’s light into its component wavelengths, like how a prism can separate normal white light into the colors of the rainbow.
“As a planet passes in front of its star, some of the star’s light passes through the planet’s atmosphere where it interacts with the elements and molecules in the atmosphere,” said Aaron Bello-Arufe, a postdoctoral researcher at JPL and the first author of the paper. “Specific elements will absorb specific wavelengths of light, creating a fingerprint in the spectrum of light that JWST detects that reflects the atmosphere’s composition.”
The spectrum during the transit is compared to baseline measurements of the star’s light established through about 20 consecutive hours of observations by JWST. The transit itself lasts about seven hours, which is much longer than the transits for hot Jupiters, which can be an hour or less. The differences between the baseline and transit spectra show which wavelengths of light are being absorbed by the planet’s atmosphere and are used to identify the elements and molecules that comprise the atmosphere, the researchers explained.
“When we compared the spectra during the transit to the baseline, we saw that the atmosphere blocked the wavelengths of starlight absorbed by methane,” Bello-Arufe said. “Models for the composition of temperate, gas-giant exoplanets had predicted that they would contain methane, so it is good to get confirmation that our theories are accurate.”
In addition to methane, the team’s observations gave hints that the atmosphere also contained ammonia and carbon dioxide.
“With additional observations of this planet, we could establish the relative abundance of these various gases in its atmosphere,” Hu said. “This more complete picture of a temperate gas giant’s atmosphere can then be used to improve our models and potentially better understand how planets and their atmospheres form and evolve, including for Earth. The success of this first study of a temperate giant planet’s atmosphere also gives us confidence to dedicate more resources and observation time to study other similar planets. We can then see if this planet is unique or if there are general shared characteristics for this type of planet.”
In addition to Hu and Bello-Arufe, the research team included Mantas Zilinskas, Jeehyun Yang, Armen Tokadjian and Mario Damiano at JPL; Luis Welbanks at Arizona State University; Guangwei Fu and David K. Sing at Johns Hopkins University; Michael Greklek-McKeon at the Carnegie Institution for Science; Jonathan Gomez Barrientos and Heather A. Knutson at the California Institute of Technology; and Xi Zhang at the University of California Santa Cruz.
NASA, through a grant from the Space Telescope Science Institute, funded the research.
Journal
The Astronomical Journal
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Methane on the Temperate Exo-Saturn TOI-199 b
Article Publication Date
20-May-2026
No comments:
Post a Comment