Sun news May 21: Far side hides fiery active regions
Today’s top story: The Earth-facing side of the sun is currently quiet, but its far side tells a different story. Large, fiery sunspot regions are lurking out of view. How do we know? Firstly, NASA’s Perseverance rover has used its vantage point on Mars to image this activity. Plus, specialists have been able to monitor these hidden regions using helioseismic echoes from the far side. Excitingly, these sunspot regions are approaching the eastern horizon of the sun from our perspective on Earth, and should soon rotate into our view. Stay tuned to see what these fiery regions bring to the table!
Past 24 hours of sun news
(11 UTC May 20 – 11 UTC May 21)
Flare activity
Over the past day, solar activity dropped from low to very low levels. The sun produced only B-class (weak) flares. In total, it fired just 5 B-class flares, down from yesterday’s 8.
- Strongest flare: B9.2 from AR4443 in the southeast, peaking at 16:11 UTC on May 20.
- Lead flare producer: A tie at the top once more; AR4441 and AR4443 each fired 2 B-class flares.
Sunspot regions
This morning, the sun shows 4 numbered active regions on its Earth-facing side. All four carry simple alpha or beta configurations. All four appear stable or in decay.
AR4436, the prolific flare producer of recent days, now sits at the very edge of the northwest horizon. Solar rotation is about to carry it to the far side. From this position, any strong flare or coronal mass ejection (CME) it produces could funnel directly toward Earth along the Parker Spiral. However, expectations are not high, as this region has reduced to a simpler beta configuration.
Blasts from the sun?
Available coronagraph imagery showed no Earth-directed coronal mass ejections (CMEs) over the past day.
Past 24 hours in space weather
Solar wind
Solar wind speeds averaged moderate levels through the entire period. Meanwhile, the interplanetary magnetic field (IMF) stayed weak throughout.
Bz and magnetic coupling
The Bz component kept shifting between north and south through the past day. However, it pointed mostly northward on most occasions. As of 11 UTC on May 21, the Bz has turned south-oriented. As always, a sustained southward Bz favors auroral displays.
Earth’s magnetic field
After yesterday’s Kp 4 disturbance, Earth’s magnetic field eased to quiet-to-unsettled levels over the past 24 hours (Kp 1–3). Currently, at 11 UTC on May 21, Earth’s magnetic field sits slightly above Kp level 2.
What’s ahead? Sun–Earth forecast
Flare activity forecast
Forecasters expect low levels of flare activity to continue. Chances for M-class (moderate) flares hold at 20% today. Meanwhile, X-class (strong) flare chances remain at 5%.
The main drivers: AR4436 is now over the northwest limb, taking its prolific flare production to the far side. AR4441 and AR4442 produced only B-class flares. However, forecasters await the appearance of fiery active regions currently on the far side. Their arrival could change the situation on the Earth-facing disk entirely.
Geomagnetic activity forecast
- May 21: Expect quiet-to-unsettled conditions. Solar wind from a coronal hole may provide some active enhancements.
- May 22–23: Quiet-to-unsettled levels should continue as influences of fast solar wind from a coronal hole persist. No significant geomagnetic drivers are in play.
Sun news May 20: Solar material glances Earth, sun erupts again
The sun-stuff glancing blow we had been waiting for finally arrived last night. The coronal mass ejection (CME) from May 16 swept past Earth and pushed geomagnetic activity to Kp 4 (active) levels, falling just short of the G1 (minor) geomagnetic storm threshold. This disturbance is now starting to wane. Meanwhile on the sun, a beautiful eruption hurled another blob of solar stuff into space at 10:26 UTC yesterday. But after modeling and analysis, forecasters determined that no component of this CME is headed our way at Earth.
Past 24 hours of sun news
(11 UTC May 19 – 11 UTC May 20)
Flare activity
Over the past day, solar activity continued at low levels. In total, the sun sparked 12 flares: 8 C-class (common) and 4 B-class (weak).
- Strongest flare: C2.1 from AR4436 in the northwest, peaking at 20:00 UTC on May 19.
- Lead flare producer: AR4436 once again topped the list. It fired 10 of the 12 flares, including 7 C-class and 3 B-class events. The remaining 2 flares came from other regions on the disk.
Sunspot regions
Currently, 5 numbered active regions populate the Earth-facing side of the solar disk. Notably, all five sunspot regions now carry simple alpha configurations. All five appear stable or in decay. As a result, the risk of strong flares stays low from the currently numbered regions.
Blasts from the sun?
Available coronagraph imagery showed no Earth-directed coronal mass ejections (CMEs) over the past day. The eruption tied to the B8.2 flare from AR4440 launched material into space. However, forecasters confirmed that none is heading toward Earth.
Past 24 hours in space weather
Solar wind
Solar wind speeds decreased from moderate-high levels through the period. By 11 UTC on May 20, speeds have dropped to moderate-low levels. The glancing blow from the May 16 CME has started to wane. The interplanetary magnetic field (IMF) stayed weak throughout the past day.
Bz and magnetic coupling
The Bz component pointed mostly southward through the past day. Only a couple of weak northward peaks occurred. As of 11 UTC on May 20, the Bz remains south-oriented. As always, a sustained southward Bz favors auroral displays.
Earth’s magnetic field
Over the past day, Earth’s magnetic field reached active levels (Kp 3–4). The anticipated geomagnetic disturbance from the passing CME material arrived as a Kp 4 disturbance. It lasted for four consecutive three-hour periods. However, it did not cross the G1 storm threshold. Since then, Earth’s magnetic field has eased back to Kp 3.
Sun news May 19: Is recent sun-stuff grazing Earth?
The glancing blow from a blast of sun-stuff we’ve been waiting for – a traveling coronal mass ejection, or CME – might be here. Solar wind speeds started climbing to moderate-high levels at 5:30 UTC this morning. Meanwhile, the interplanetary magnetic field (IMF) also showed a slight increase around 6:30 UTC. These signatures suggest the CME’s glancing effects. This sun blast – consisting of solar materials and magnetic fields – left the sun on May 16. Forecasters expect unsettled-to-active conditions today. An isolated G1 (minor) geomagnetic storm is possible as the CME material sweeps past.
Past 24 hours of sun news
(11 UTC May 18 – 11 UTC May 19)
Flare activity
On the solar front, over the past day, activity returned to low levels. The sun fired only 2 C (common) flares and 6 B (weak) flares. AR4436 once again dominated, producing 7 of the 8 events. Even so, the region still packs energy.
- Strongest flare: C2.1 from AR4436, peaking at 7:40 UTC on May 19.
- Lead flare producer: AR4436 once again topped the list. It fired 7 of the 8 events.
Sunspot regions
Currently, 5 numbered active regions populate the Earth-facing side of the solar disk. All five sunspot regions stayed stable during this period. They carry simple alpha or beta configurations. As a result, the risk of strong flares remains low from the currently numbered regions.
Blasts from the sun?
Available coronagraph imagery showed no Earth-directed coronal mass ejections (CMEs) over the past day.
Past 24 hours in space weather
Solar wind
Solar wind speeds averaged moderate levels through most of the period. However, starting at 5:30 UTC this morning on May 19, speeds began climbing to moderate-high levels. This increase may signal the glancing arrival of the CME that left the sun on May 16.
Bz and magnetic coupling
The Bz component pointed mostly southward through the past day. A couple of northward peaks occurred. But the dominant story was the sustained southward orientation. In particular, a sustained southward dip began at 1 UTC on May 19 and continued through the morning. A sustained southward Bz favors auroral displays.
Earth’s magnetic field
Over the past day, Earth’s magnetic field ranged from quiet to unsettled (Kp 2–3). Currently, the Kp index sits at level 3. But with the CME material potentially arriving, that number could climb.
Sun news May 18: Sun-stuff racing toward Earth, aurora possible
A knotty blob of sun-stuff launched from the sun on Saturday is now racing through interplanetary space. Analysts currently think this coronal mass ejection (CME) could give Earth a glancing blow as early as overnight tonight. The impact could spark G1 (minor) to G2 (moderate) geomagnetic storms. And that could mean auroras visible from northern latitudes, including northern Scotland and Scandinavia. Share your aurora photos with us!
Past 24 hours of sun news
(11 UTC May 17 – 11 UTC May 18)
Flare activity
Over the past day, solar activity held at moderate. In total, the sun fired 9 flares: 4 C-class (common) and several B-class (weak) events.
- Strongest flare: C9.7 from AR4436, peaking at 20:42 UTC on May 17. This event was accompanied by a notably strong 370-solar-flux-unit radio burst.
- Lead flare producer: AR4436 topped the list. It fired at least 6 of the 9 tracked events, including the C9.7 and multiple B-class flares.
Sunspot regions
The Earth-facing solar disk currently shows 7 numbered active regions.
Blasts from the sun?
The major CME story centers on the complex eruption on May 16, which is now en route to Earth. A wide, fast CME appeared in SOHO LASCO C2 and C3 imagery at 16:36 UTC on May 16. It was tied to the M1.9 flare from AR4436. Coronal dimming and a Type IV radio sweep accompanied the eruption. The bulk of the ejecta soared out to the northwest. However, modeling indicates some will give Earth a glancing blow around 0:00 UTC on May 19. Kp estimates range from 3 to 5, depending on the CME’s magnetic orientation upon arrival. That points to potential G1 (minor) storm conditions, with a chance of borderline G2 (moderate).
Past 24 hours in space weather
Solar wind
Solar wind speeds gradually decreased through the period. That’s as the coronal hole’s high-speed solar wind stream continued its slow fadeout. Meanwhile, the total interplanetary magnetic field stayed relatively weak.
Bz and magnetic coupling
The Bz component remained near neutral. No sustained southward dips occurred. That explains why geomagnetic conditions stayed quiet despite the elevated solar wind speeds. Without a sustained southward Bz, Earth’s magnetic shield stays effectively closed.
Earth’s magnetic field
Over the past day, Earth’s magnetic field stayed at quiet levels (Kp 1–2).
The sun in recent days
Earlier sun images
Sun images from our community
More sun images from our community
We sometimes feature sun images obtained using hydrogen-alpha filters. Read why.
Bottom line: Sun news for May 21, 2026: The far side is hiding some fiery active regions. Images from the Perseverance rover on Mars show what’s coming our way.
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