An unexpectedly robust photo voltaic storm rocked our planet on April 23, 2023, sparking auroras as far south as southern Texas within the U.S. and taking the world unexpectedly.
Two days earlier, the Solar blasted a coronal mass ejection (CME) — a cloud of energetic particles, magnetic fields, and photo voltaic materials — towards Earth. House scientists took discover, anticipating it may trigger disruptions to Earth’s magnetic discipline, referred to as a geomagnetic storm. However the CME wasn’t particularly quick or large, and it was preceded by a comparatively weak photo voltaic flare, suggesting the storm can be minor. Nevertheless it turned extreme.
Utilizing NASA heliophysics missions, new research of this storm and others are serving to scientists be taught why some CMEs have extra intense results — and higher predict the impacts of future photo voltaic eruptions on our lives.
A paper revealed within the Astrophysical Journal on March 31 suggests the CME’s orientation relative to Earth possible triggered the April 2023 storm to develop into surprisingly robust.
The researchers gathered observations from 5 heliophysics spacecraft throughout the interior photo voltaic system to review the CME intimately because it emerged from the Solar and traveled to Earth.
They seen a massive coronal gap close to the CME’s birthplace. Coronal holes are areas the place the solar wind — a stream of particles flowing from the Solar — floods outward at greater than regular speeds.
“The quick photo voltaic wind coming from this coronal gap acted like an air present, nudging the CME away from its authentic straight-line path and pushing it nearer to Earth’s orbital aircraft,” mentioned the paper’s lead creator, Evangelos Paouris of the Johns Hopkins Utilized Physics Laboratory in Laurel, Maryland. “Along with this deflection, the CME additionally rotated barely.”
Paouris says this turned the CME’s magnetic fields reverse to Earth’s magnetic discipline and held them there — permitting extra of the Solar’s power to pour into Earth’s atmosphere and intensifying the storm.
In the meantime, NASA’s GOLD (World-scale Observations of Limb and Disk) mission revealed one other surprising consequence of the April 2023 storm at Earth.
Earlier than, throughout, and after the storm, GOLD studied the temperature within the center thermosphere, part of Earth’s higher ambiance about 85 to 120 miles overhead. Through the storm, temperatures elevated all through GOLD’s vast discipline of view over the Americas. However surprisingly, after the storm, temperatures dropped about 90 to 198 levels Fahrenheit decrease than they had been earlier than the storm (from about 980 to 1,070 levels Fahrenheit earlier than the storm to 870 to 980 levels Fahrenheit afterward).
“Our measurement is the primary to point out widespread cooling within the center thermosphere after a powerful storm,” mentioned Xuguang Cai of the College of Colorado, Boulder, lead creator of a paper about GOLD’s observations revealed within the journal JGR House Physics on April 15, 2025.
The thermosphere’s temperature is essential, as a result of it impacts how a lot drag Earth-orbiting satellites and area particles expertise.
“When the thermosphere cools, it contracts and turns into much less dense at satellite tv for pc altitudes, lowering drag,” Cai mentioned. “This could trigger satellites and area particles to remain in orbit longer than anticipated, rising the chance of collisions. Understanding how geomagnetic storms and photo voltaic exercise have an effect on Earth’s higher ambiance helps defend applied sciences all of us depend on — like GPS, satellites, and radio communications.”
To foretell when a CME will set off a geomagnetic storm, or be “geoeffective,” some scientists are combining observations with machine studying. A paper revealed final November within the journal Photo voltaic Physics describes one such method referred to as GeoCME.
Machine studying is a sort of synthetic intelligence during which a pc algorithm learns from information to determine patterns, then makes use of these patterns to make choices or predictions.
Scientists educated GeoCME by giving it photos from the NASA/ESA (European House Company) SOHO (Photo voltaic and Heliospheric Observatory) spacecraft of various CMEs that reached Earth together with SOHO photos of the Solar earlier than, throughout, and after every CME. They then advised the mannequin whether or not every CME produced a geomagnetic storm.
Then, when it was given photos from three totally different science devices on SOHO, the mannequin’s predictions had been extremely correct. Out of 21 geoeffective CMEs, the mannequin appropriately predicted all 21 of them; of seven non-geoeffective ones, it appropriately predicted 5 of them.
“The algorithm exhibits promise,” mentioned heliophysicist Jack Eire of NASA’s Goddard House Flight Heart in Greenbelt, Maryland, who was not concerned within the research. “Understanding if a CME shall be geoeffective or not may help us defend infrastructure in area and technological techniques on Earth. This paper exhibits machine studying approaches to predicting geoeffective CMEs are possible.”
Throughout a extreme geomagnetic storm in Might 2024 — the strongest to rattle Earth in over 20 years — NASA’s STEREO (Photo voltaic Terrestrial Relations Observatory) measured the magnetic discipline construction of CMEs as they handed by.
When a CME headed for Earth hits a spacecraft first, that spacecraft can typically measure the CME and its magnetic discipline immediately, serving to scientists decide how robust the geomagnetic storm shall be at Earth. Sometimes, the primary spacecraft to get hit are a million miles from Earth towards the Solar at a spot referred to as Lagrange Level 1 (L1), giving us solely 10 to 60 minutes superior warning.
By probability, through the Might 2024 storm, when a number of CMEs erupted from the Solar and merged on their approach to Earth, NASA’s STEREO-A spacecraft occurred to be between us and the Solar, about 4 million miles nearer to the Solar than L1.
A paper revealed March 17, 2025, within the journal House Climate studies that if STEREO-A had served as a CME sentinel, it may have offered an correct prediction of the ensuing storm’s energy 2 hours and 34 minutes sooner than a spacecraft may at L1.
In response to the paper’s lead creator, Eva Weiler of the Austrian House Climate Workplace in Graz, “No different Earth-directed superstorm has ever been noticed by a spacecraft positioned nearer to the Solar than L1.”
By Vanessa Thomas
NASA’s Goddard Space Flight Center, Greenbelt, Md.