The sun had a busy week. Between Thursday afternoon and Friday morning, our star fired off five M-class solar flares and capped the sequence with an X2.4-class eruption — the stronger, rarer category that puts space weather forecasters on alert. A coronal mass ejection (CME) is now traveling toward Earth, and NOAA is forecasting a G1-class geomagnetic storm for Sunday, April 26. That means there's a real chance of northern lights visible well beyond the Arctic Circle this weekend, depending on where you live and how the storm develops.
Here's everything you need to know about what happened, what it means, and how to see the aurora if conditions cooperate — explained clearly, without the hype.
The 24-Hour Eruption Sequence: What Actually Happened
On Thursday, April 23, 2026, the sun produced five M-class solar flares in rapid succession. M-class flares sit in the middle of the solar flare classification scale — significant enough to cause brief radio blackouts on the sunlit side of Earth, but below the threshold of the most powerful events. NASA's Solar Dynamics Observatory tracked the activity in real time, and images from NOAA's SOHO Observatory captured both the sunspot regions responsible and a coronal mass ejection launching outward from the solar surface in the direction of Earth.
Then on Friday, April 24, the sun escalated. An X2.4-class flare erupted — a considerably more powerful event. X-class flares are the strongest category in NOAA's classification system, and an X2.4 is well above the threshold that typically triggers radio blackouts across the sunlit hemisphere. During major X-class events, high-frequency radio communications — used by aviation, maritime operations, and amateur radio operators — can be disrupted or cut out entirely for minutes to hours.
NOAA forecasters expect continued flare activity on Friday, April 25, and into the weekend as the active sunspot regions rotate across the solar disk.
Solar Flares vs. CMEs vs. Geomagnetic Storms: Getting the Science Right
One of the most common misconceptions about space weather is that solar flares cause auroras. They don't — at least not directly. Understanding the distinction matters if you want to correctly interpret forecasts.
Solar flares are intense bursts of electromagnetic radiation — X-rays and ultraviolet light — that travel at the speed of light and reach Earth in about eight minutes. Their immediate effects are radio blackouts and, in rare cases, disruption to GPS accuracy. They do not send particles toward Earth in the way that triggers auroras.
Coronal mass ejections (CMEs) are the actual culprits behind geomagnetic storms and aurora displays. CMEs are massive clouds of magnetized plasma ejected from the sun's corona. They travel much slower than light — typically taking one to three days to reach Earth. When a CME's magnetic field connects with Earth's magnetosphere in the right orientation (southward-pointing), it can drive electrical currents through our magnetic field and send energized particles cascading into the upper atmosphere near the poles.
Geomagnetic storms are what those cascading particles create. NOAA rates them on a five-point G-scale, from G1 (Minor) to G5 (Extreme). The CME from this week's activity is expected to graze Earth's magnetic field on Sunday, April 26, producing a G1-class storm. "Graze" is the key word — the CME isn't on a direct collision course, which is why the forecast is for a minor rather than moderate or severe event. However, even a glancing blow can produce auroras visible at mid-latitudes under the right conditions.
What a G1 Storm Actually Means for This Weekend
A G1 storm is the lowest tier of the geomagnetic storm scale, but that framing undersells what can happen visually. During a G1 event, aurora displays are possible at latitudes as low as 60° geomagnetic — roughly corresponding to the northern tier of the continental United States (northern Minnesota, Michigan's Upper Peninsula, Maine), southern Canada, Scandinavia, and similar latitudes in the Southern Hemisphere.
If the CME arrives with a stronger southward magnetic field component than currently expected, the storm could intensify. Space weather forecasting carries significant uncertainty because the critical measurement — the orientation of the CME's magnetic field — can only be confirmed roughly 15 to 60 minutes before impact, when NOAA's DSCOVR satellite, positioned at the L1 Lagrange point between Earth and the sun, detects the incoming solar wind.
DSCOVR measures solar wind speed and magnetic intensity, providing that narrow but critical warning window. When DSCOVR detects a strongly southward-pointing field, forecasters can upgrade storm predictions in near-real time — which is why serious aurora hunters keep NOAA's Space Weather Prediction Center open in a browser tab on nights like this weekend.
Beyond auroras, G1 storms can cause weak fluctuations in power grids, minor impacts to satellite operations, and slight degradation in high-frequency radio communications at higher latitudes. Nothing catastrophic at this level — but infrastructure operators do take note.
Where and When to Watch for Aurora This Weekend
If you're in a position to chase the aurora this weekend, the setup is straightforward: get away from light pollution, face north (in the Northern Hemisphere), and be patient. The CME is forecast to arrive Sunday, April 26, with the storm potentially peaking in the evening hours when the aurora oval is most visible from mid-latitudes.
Serious aurora watchers use a combination of NOAA's 3-day geomagnetic forecast and the real-time Kp index (a measure of global geomagnetic activity on a 0–9 scale) to determine viewing likelihood. For mid-latitude viewers in the U.S., a Kp of 5 or higher generally brings the aurora into view on the horizon. A G1 storm corresponds to a Kp of 5.
For viewing, the clearest skies and darkest horizons matter most. A good pair of photography tripods and a camera capable of long exposures will capture aurora displays that the naked eye might barely perceive — cameras are often more sensitive to the greens and reds of aurora than human vision in low light. A wide-angle lens for astrophotography dramatically improves your chances of capturing the full arc. If you want to observe but not photograph, a reclining camping chair for stargazing is the most practical investment — auroras can last hours and neck strain is real.
For solar observation in general (not recommended without proper equipment for aurora watching), a solar telescope with proper solar filter lets you observe sunspots and active regions safely. Never attempt to observe the sun without certified solar filters — standard sunglasses are not adequate protection. Dedicated ISO-certified solar viewing glasses are the minimum safe option for unaided solar observation.
The Unexpected Bonus: Comet Pan-STARRS Near the Sun
Buried in this week's space weather news is a genuinely unusual astronomical coincidence. Comet C/2025 R3 (Pan-STARRS) appeared in solar observatory images this week as it makes its closest approach to the sun — perihelion is forecast for April 27, 2026, the day after the CME is expected to arrive.
The comet was captured in NASA spacecraft time-lapse imagery alongside the solar flare activity, creating a striking visual juxtaposition. Solar observatories like SOHO routinely capture sungrazing comets — comets that pass extremely close to the sun — because their wide field of view around the solar corona makes them ideal for detecting objects that would otherwise be lost in the sun's glare.
Whether C/2025 R3 survives its close solar passage and becomes visible to the naked eye afterward depends on how intact its nucleus remains after perihelion heating. Comets are notoriously unpredictable performers — some emerge brighter than expected, some disintegrate entirely. Astronomers will have a clearer picture in the days following April 27.
Analysis: What This Week's Activity Tells Us About Solar Cycle 25
The rapid-fire sequence of M-class flares followed by an X2.4 is not random noise — it's a data point in the broader story of Solar Cycle 25, which has been running significantly hotter than forecasters initially predicted.
Solar cycles follow roughly 11-year patterns of activity, running from solar minimum (fewest sunspots, least flare activity) to solar maximum and back. When Cycle 25 began in 2019, NOAA and NASA's Solar Cycle 25 Prediction Panel forecast a relatively moderate cycle, comparable to the weak Cycle 24. Instead, Cycle 25 has been exceeding those predictions consistently since 2023, with sunspot numbers and flare frequency tracking well above the predicted average.
That matters for practical reasons beyond aurora tourism. More intense solar cycles mean higher cumulative radiation exposure for astronauts and passengers on polar aviation routes. They mean more frequent disruption to high-frequency radio communications and potential stress on power grid infrastructure at high latitudes. The March 2024 geomagnetic storm — the strongest in two decades, reaching G5 intensity — produced aurora displays visible as far south as Mexico and generated widespread media coverage partly because it was so unexpected by the public, even as forecasters had been tracking the trend.
This week's activity fits a pattern: an active sun producing complex, multi-event eruption sequences from large sunspot regions. The fact that five M-class flares and an X2.4 occurred within 24 hours suggests a particularly energetic active region rotating across the solar disk. Forecasters expect continued activity through the weekend, and additional CMEs — potentially more Earth-directed than the current one — remain possible.
The honest assessment: this is an active period of solar weather, not a crisis. The infrastructure threats from a G1 storm are minimal. But it is a reminder that Solar Cycle 25 has consistently outperformed its forecast, and the peak activity window may not yet be behind us.
Frequently Asked Questions
Can solar flares directly harm humans on Earth's surface?
No. Earth's atmosphere and magnetic field provide robust shielding against the radiation from solar flares. The X-rays from even the strongest flares are absorbed by the upper atmosphere before reaching ground level. The populations with genuine exposure risk during major solar events are astronauts in deep space or aboard the International Space Station, and airline passengers on polar routes (who receive slightly elevated radiation doses during X-class events, though still within acceptable limits). For everyone on the ground, solar flares pose no direct health risk.
How do I know if the aurora will be visible where I live?
The most reliable tool is NOAA's Space Weather Prediction Center (spaceweather.gov), which publishes the 3-day geomagnetic storm outlook and the real-time Kp index. The Kp value tells you how far south the aurora oval is expanding — higher Kp means aurora visible at lower latitudes. For the current forecast (G1 storm on April 26), viewers in the northern U.S. and southern Canada have a reasonable shot if skies are clear and they're away from city lights. The window typically opens 30–60 minutes after DSCOVR confirms CME arrival.
What's the difference between M-class and X-class solar flares?
NOAA classifies solar flares on a logarithmic scale: A, B, C, M, and X, where each step represents a roughly 10-fold increase in X-ray energy output. M-class flares (M1 through M9) are significant events capable of causing brief radio blackouts on the sun-facing side of Earth. X-class flares begin at 10 times the energy of an M1 and are numbered continuously (X1, X2, X10, etc.). An X2.4, like Friday's event, is roughly 24 times more energetic than an M1. The strongest flare ever recorded was an estimated X28 in November 2003 — so powerful it saturated the measuring instruments.
Will the X2.4 flare itself cause problems?
The X2.4 flare likely caused a significant radio blackout on the Earth-facing hemisphere shortly after it erupted on April 24 — this is the immediate, light-speed effect of X-ray radiation hitting the ionosphere. That disruption lasts minutes to a few hours at most. Any longer-duration effects (geomagnetic storm, aurora) depend on whether the flare was accompanied by a CME, and whether that CME is Earth-directed. The current storm forecast is tied to an earlier CME from the M-class activity, not necessarily the X2.4 itself, though additional CMEs from the X-class event will be assessed by forecasters over the coming day.
Is the approaching comet related to the solar flares?
No — the timing is coincidental. Comet C/2025 R3 (Pan-STARRS) is following its orbital path toward perihelion on April 27 entirely independent of solar activity. Comets can appear in solar observatory images because instruments like SOHO's LASCO coronagraph image a wide field around the sun and are designed to track objects in the inner solar system. The appearance of a comet in the same frames as active solar flaring is a visual coincidence, not a physical connection.
What to Watch For in the Coming Days
The active sunspot region responsible for this week's flaring hasn't rotated off the Earth-facing disk yet, which means additional flares and potentially additional CMEs remain likely through the weekend. Space weather forecasting is inherently probabilistic — the G1 storm on Sunday could arrive stronger or weaker than projected, or the CME could miss Earth's magnetic field more cleanly than expected.
The practical advice: keep NOAA's Space Weather Prediction Center bookmarked if you're hoping to see the aurora. Watch the Kp index on Saturday night and Sunday evening. If it climbs above 5 and you have clear, dark skies at latitudes above 50°N, start looking north. If you're in the northern tier of the continental U.S. or southern Canada, the same applies — with the caveat that a glancing CME at G1 intensity is not a guarantee of visible aurora at those latitudes, just a meaningful chance.
Solar Cycle 25 has repeatedly outperformed its forecast. This week's flare sequence is a reminder that the sun is still very much in an active phase, and the next major event — whenever it comes — is worth taking seriously.
