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By NASA
An unexpectedly strong solar storm rocked our planet on April 23, 2023, sparking auroras as far south as southern Texas in the U.S. and taking the world by surprise.
Two days earlier, the Sun blasted a coronal mass ejection (CME) — a cloud of energetic particles, magnetic fields, and solar material — toward Earth. Space scientists took notice, expecting it could cause disruptions to Earth’s magnetic field, known as a geomagnetic storm. But the CME wasn’t especially fast or massive, and it was preceded by a relatively weak solar flare, suggesting the storm would be minor. But it became severe.
Using NASA heliophysics missions, new studies of this storm and others are helping scientists learn why some CMEs have more intense effects — and better predict the impacts of future solar eruptions on our lives.
During the night of April 23 to 24, 2023, a geomagnetic storm produced auroras that were witnessed as far south as Arizona, Arkansas, and Texas in the U.S. This photo shows green aurora shimmering over Larimore, North Dakota, in the early morning of April 24. Copyright Elan Azriel, used with permission Why Was This Storm So Intense?
A paper published in the Astrophysical Journal on March 31 suggests the CME’s orientation relative to Earth likely caused the April 2023 storm to become surprisingly strong.
The researchers gathered observations from five heliophysics spacecraft across the inner solar system to study the CME in detail as it emerged from the Sun and traveled to Earth.
They noticed a large coronal hole near the CME’s birthplace. Coronal holes are areas where the solar wind — a stream of particles flowing from the Sun — floods outward at higher than normal speeds.
“The fast solar wind coming from this coronal hole acted like an air current, nudging the CME away from its original straight-line path and pushing it closer to Earth’s orbital plane,” said the paper’s lead author, Evangelos Paouris of the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland. “In addition to this deflection, the CME also rotated slightly.”
Paouris says this turned the CME’s magnetic fields opposite to Earth’s magnetic field and held them there — allowing more of the Sun’s energy to pour into Earth’s environment and intensifying the storm.
The strength of the April 2023 geomagnetic storm was a surprise in part because the coronal mass ejection (CME) that produced it followed a relatively weak solar flare, seen as the bright area to the lower right of center in this extreme ultraviolet image of the Sun from NASA’s Solar Dynamics Observatory. The CMEs that produce severe geomagnetic storms are typically preceded by stronger flares. However, a team of scientists think fast solar wind from a coronal hole (the dark area below the flare in this image) helped rotate the CME and made it more potent when it struck Earth. NASA/SDO Cool Thermosphere
Meanwhile, NASA’s GOLD (Global-scale Observations of Limb and Disk) mission revealed another unexpected consequence of the April 2023 storm at Earth.
Before, during, and after the storm, GOLD studied the temperature in the middle thermosphere, a part of Earth’s upper atmosphere about 85 to 120 miles overhead. During the storm, temperatures increased throughout GOLD’s wide field of view over the Americas. But surprisingly, after the storm, temperatures dropped about 90 to 198 degrees Fahrenheit lower than they were before the storm (from about 980 to 1,070 degrees Fahrenheit before the storm to 870 to 980 degrees Fahrenheit afterward).
“Our measurement is the first to show widespread cooling in the middle thermosphere after a strong storm,” said Xuguang Cai of the University of Colorado, Boulder, lead author of a paper about GOLD’s observations published in the journal JGR Space Physics on April 15, 2025.
The thermosphere’s temperature is important, because it affects how much drag Earth-orbiting satellites and space debris experience.
“When the thermosphere cools, it contracts and becomes less dense at satellite altitudes, reducing drag,” Cai said. “This can cause satellites and space debris to stay in orbit longer than expected, increasing the risk of collisions. Understanding how geomagnetic storms and solar activity affect Earth’s upper atmosphere helps protect technologies we all rely on — like GPS, satellites, and radio communications.”
Predicting When Storms Strike
To predict when a CME will trigger a geomagnetic storm, or be “geoeffective,” some scientists are combining observations with machine learning. A paper published last November in the journal Solar Physics describes one such approach called GeoCME.
Machine learning is a type of artificial intelligence in which a computer algorithm learns from data to identify patterns, then uses those patterns to make decisions or predictions.
Scientists trained GeoCME by giving it images from the NASA/ESA (European Space Agency) SOHO (Solar and Heliospheric Observatory) spacecraft of different CMEs that reached Earth along with SOHO images of the Sun before, during, and after each CME. They then told the model whether each CME produced a geomagnetic storm.
Then, when it was given images from three different science instruments on SOHO, the model’s predictions were highly accurate. Out of 21 geoeffective CMEs, the model correctly predicted all 21 of them; of 7 non-geoeffective ones, it correctly predicted 5 of them.
“The algorithm shows promise,” said heliophysicist Jack Ireland of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who was not involved in the study. “Understanding if a CME will be geoeffective or not can help us protect infrastructure in space and technological systems on Earth. This paper shows machine learning approaches to predicting geoeffective CMEs are feasible.”
The white cloud expanding outward in this image sequence is a coronal mass ejection (CME) that erupted from the Sun on April 21, 2023. Two days later, the CME struck Earth and produced a surprisingly strong geomagnetic storm. The images in this sequence are from a coronagraph on the NASA/ESA (European Space Agency) SOHO (Solar and Heliospheric Observatory) spacecraft. The coronagraph uses a disk to cover the Sun and reveal fainter details around it. The Sun’s location and size are indicated by a small white circle. The planet Jupiter appears as a bright dot on the far right. NASA/ESA/SOHO Earlier Warnings
During a severe geomagnetic storm in May 2024 — the strongest to rattle Earth in over 20 years — NASA’s STEREO (Solar Terrestrial Relations Observatory) measured the magnetic field structure of CMEs as they passed by.
When a CME headed for Earth hits a spacecraft first, that spacecraft can often measure the CME and its magnetic field directly, helping scientists determine how strong the geomagnetic storm will be at Earth. Typically, the first spacecraft to get hit are one million miles from Earth toward the Sun at a place called Lagrange Point 1 (L1), giving us only 10 to 60 minutes advanced warning.
By chance, during the May 2024 storm, when several CMEs erupted from the Sun and merged on their way to Earth, NASA’s STEREO-A spacecraft happened to be between us and the Sun, about 4 million miles closer to the Sun than L1.
A paper published March 17, 2025, in the journal Space Weather reports that if STEREO-A had served as a CME sentinel, it could have provided an accurate prediction of the resulting storm’s strength 2 hours and 34 minutes earlier than a spacecraft could at L1.
According to the paper’s lead author, Eva Weiler of the Austrian Space Weather Office in Graz, “No other Earth-directed superstorm has ever been observed by a spacecraft positioned closer to the Sun than L1.”
Earth’s Lagrange points are places in space where the gravitational pull between the Sun and Earth balance, making them relatively stable locations to put spacecraft. NASA By Vanessa Thomas
NASA’s Goddard Space Flight Center, Greenbelt, Md.
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By European Space Agency
Today, the European Space Agency’s Proba-3 mission unveils its first images of the Sun’s outer atmosphere – the solar corona. The mission’s two satellites, able to fly as a single spacecraft thanks to a suite of onboard positioning technologies, have succeeded in creating their first ‘artificial total solar eclipse’ in orbit. The resulting coronal images demonstrate the potential of formation flying technologies, while delivering invaluable scientific data that will improve our understanding of the Sun and its enigmatic atmosphere.
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By European Space Agency
Video: 00:01:40 Proba-3 artificially created what is normally a rare natural phenomenon: a total solar eclipse.
In a world first, ESA’s Proba-3 satellites flew in perfect formation, blocking the Sun’s bright disc to reveal its fiery corona. This enigmatic outer layer burns millions of degrees hotter than the Sun’s surface and drives the solar storms that can disrupt life on Earth.
With its first artificial eclipse, Proba-3 has captured detailed images of this mysterious region, offering scientists new insights into our star’s behaviour.
Read the full story here.
Access the related broadcast qality footage.
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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
Skywatching Skywatching Home What’s Up Meteor Showers Eclipses Daily Moon Guide More Tips & Guides Skywatching FAQ Night Sky Network Planets, Solstice, and the Galaxy
Venus and Saturn separate, while Mars hangs out in the evening. Plus the June solstice, and dark skies reveal our home galaxy in all of its glory.
Skywatching Highlights
All Month – Planet Visibility:
Venus: Rises about 2 hours before the Sun in June, and shines very brightly, low in the eastern sky, in the morning all month. Mars: Visible in the west for a couple of hours after sunset all month. Drops lower in the sky as June continues, and passes very close to Regulus in the constellation Leo on June 16 and 17. (They will be about half a degree apart, or the width of the full moon.) Jupiter: Visible quite low in the west after sunset for the first week of June, then lost in the Sun’s glare after. Will re-appear in July in the morning sky. Mercury: Becomes visible low in the west about 30 to 45 minutes after sunset in the last week and a half of June. Saturn: Rises around 3 a.m. in early June, and around 1 a.m. by the end of the month. Begins the month near Venus in the dawn sky, but rapidly pulls away, rising higher as June goes on. Daily Highlights:
June 19 – Moon & Saturn – The third-quarter moon appears right next Saturn this morning in the hours before dawn. The pair rise in the east together around 1:30 a.m.
June 22 – Moon & Venus – Venus rises this morning next to a slender and elegant crescent moon. Look for them in the east between about 3 a.m. and sunrise.
June 20 – June Solstice – The June solstice is on June 20 for U.S. time zones (June 21 UTC). The Northern Hemisphere’s tilt toward the Sun is greatest on this day. This means the Sun travels its longest, highest arc across the sky all year for those north of the equator.
June 16 & 17 – Mars & Regulus – Mars passes quite close to the bright bluish-white star Regulus, known as the “heart” of the lion constellation, Leo. They will appear about as far apart as the width of the full moon, and should be an excellent sight in binoculars or a small telescope.
June 21-30 – Mercury becomes visible – For those with a clear view to the western horizon, Mercury becomes visible for a brief period each evening at the end of June. Look for it quite low in the sky starting 30 to 45 minutes after the Sun sets.
All month – Mars: The Red Planet can be observed for a couple of hours after dark all month. It is noticeably dimmer than it appeared in early May, as Earth speeds away in its orbit, putting greater distance between the two worlds.
All month – Milky Way core: The bright central bulge of our home galaxy, the Milky Way, is visible all night in June, continuing through August. It is best observed from dark sky locations far from bright city lights, and appears as a faint, cloud-like band arching across the sky toward the south.
Transcript
What’s Up for June? Mars grazes the lion’s heart, a connection to ancient times, and the galaxy in all its glory.
June Planet Observing
Starting with planet observing for this month, find Saturn and Venus in the eastern sky during the couple of hours before dawn each morning throughout the month. Saturn rapidly climbs higher in the sky each day as the month goes on. You’ll find the third quarter moon next to Saturn on the 19th, and a crescent moon next to Venus on the 22nd.
Sky chart showing Mercury with the crescent Moon following sunset in late June, 2025. NASA/JPL-Caltech Mercury pops up toward the end of the month. Look for it quite low in the west, just as the glow of sunset is fading. It’s highest and most visible on the 27th.
Mars is still visible in the couple of hours after sunset toward the west, though it’s noticeably fainter than it was in early May. Over several days in mid-June, Mars passes quite close to Regulus, the bright star at the heart of the constellation Leo, the lion. Have a peek on the 16th and 17th with binoculars or a small telescope to see them as close as the width of the full moon.
Sky chart showing Mars close to Regulus in the evening sky on June 16, 2025. NASA/JPL-Caltech Milky Way Core Season
June means that Milky Way “Core Season” is here. This is the time of year when the Milky Way is visible as a faint band of hazy light arching across the sky all night. You just need to be under dark skies away from bright city lights to see it. What you’re looking at is the bright central core of our home galaxy, seen edge-on, from our position within the galaxy’s disk.
Long-exposure photos make the Milky Way’s bright stars and dark dust clouds even clearer. And while our eyes see it in visible light, NASA telescopes observe the galaxy across the spectrum — peering through dust to help us better understand our origins.
However you observe it, getting out under the Milky Way in June is a truly remarkable way to connect with the cosmos.
June Solstice
June brings the summer solstice for those north of the equator, which is the winter solstice for those south of the equator. In the Northern Hemisphere, this is when the Sun is above the horizon longer than any other day, making it the longest day of the year. The situation is reversed for the Southern Hemisphere, where it’s the shortest day of the year.
Illustration from a NASA animation showing the tilt of Earth’s axis in June (Northern Hemisphere summer) with respect to the Sun, the planet’s orbit, and the North Star, Polaris. NASA’s Goddard Space Flight Center Earth’s tilted rotation is the culprit. The tilt is always in the same direction, with the North Pole always pointing toward Polaris, the North Star. And since that tilt stays the same, year round, when we’re on one side of the Sun in winter, the north part of the planet is tilted away from the Sun. But six months later, the planet moves halfway around its annual path, carrying us to the opposite side of Earth’s orbit, and the northern part of the planet now finds itself tilted toward the Sun. The June solstice is when this tilt is at its maximum. This is summertime for the north, bringing long days, lots more sunlight, and warmer temperatures.
The June solstice marks a precise moment in Earth’s orbit – a consistent astronomical signpost that humans have observed for millennia. Ancient structures from Stonehenge to Chichén Itzá were built, in part, to align with the solstices, demonstrating how important these celestial events were to many cultures.
So whether you’re experiencing long summer days in the northern hemisphere or the brief daylight hours of winter in the south, find a quiet spot to watch the sunset on this special day and you’ll be participating in one of humanity’s oldest astronomical traditions, connecting you to observers across thousands of years of human history.
Here are the phases of the Moon for June.
The phases of the Moon for June 2025. You can stay up to date on all of NASA’s missions exploring the solar system and beyond at NASA Science. I’m Preston Dyches from NASA’s Jet Propulsion Laboratory, and that’s What’s Up for this month.
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