Sun news: Huge eruption on sun’s far side!

Sun news December 17: Huge eruption on sun’s far side!

Ropes of solar material erupted over the sun’s northeast horizon in the early hours this morning (December 17). Experts didn’t detect corresponding flare activity on the Earth-facing disk. So the event must have originated on the far side of our star. The eruption also launched a cloud of solar material — commonly known as a coronal mass ejection (CME) — into space. But the launch site on the sun’s far side means this sun-stuff isn’t headed toward Earth. Judging from the prominence’s position over the sun’s northeast horizon, the sunspot region that fired out the CME might rotate into view in the coming days. If so, it’ll increase the potential for renewed activity on the Earth-facing side of the sun.

Past 24 hours: The details

(11 UTC December 15 – 11 UTC December 16)

• Flare activity: Solar activity remained at low levels over the past day, with only 6 C-class (common) and B-class (weak) flares observed (4 Cs and 2 Bs).
  • Strongest flare was a C1.9 flare from an incoming, as-yet-unnumbered active region in the sun’s northeast, at 13:51 UTC on December 16.
  • Other notable flares:
    • C1.5 from an unnumbered incoming region in the northeast at 13:43 UTC on December 16.
    • C1.1 from an unnumbered incoming active region in the northeast at 17:59 UTC on December 16.
    • C1.4 from AR4307 at 8:40 UTC on December 17.
  • Sub-C flares and background: A B7.5 flare from AR4310 at 11:11 UTC and a B8.3 flare from AR4309 at 14:54 UTC on December 16.
  • Lead flare producer: An incoming active region in the northeast led flare production with three C-class flares.
• Sunspot regions: Five numbered active regions were visible on the Earth-facing solar disk.
  • AR4310 (beta): Showed slight growth during the period.
  • AR4305 (alpha), AR4307 (beta), and AR4308 (beta) remained stable or continued decaying, with no flare production.
  • A new region, AR4311, emerged in the northeast quadrant.
• Blasts from the sun? Experts did not detect any Earth-directed coronal mass ejections (CMEs) over the past day.
• Solar wind: Solar wind speeds increased from about 600 km/s to nearly 700 km/s during the first half of December 16, then dipped to near 500 km/s before rebounding to around 600 km/s early today. The interplanetary magnetic field (IMF) strength remained steady near 6 nT. The north–south component, Bz, fluctuated between northward and southward orientations, though the strongest intervals were southward. By 10 UTC, Bz had turned northward, a configuration that limits energy transfer into Earth’s magnetosphere and suppresses auroral activity.
• Earth’s magnetic field: Geomagnetic conditions ranged from quiet to unsettled (Kp 2–3). At the time of writing, Kp remains at 3.

What’s ahead? Sun–Earth forecast

• Flare activity forecast: Solar activity is expected to remain at low levels, with a small chance of isolated M-class (moderate) flares.
  • NOAA/ SWPC estimates a 15% chance of M-class flares on December 17, mainly driven by AR4307.
  • The likelihood of an X-class (strong) flare over the next three days remains low (~1%). Number of regions currently showing the delta magnetic structure typically associated with major eruptions: zero.
• Geomagnetic activity forecast:
  • December 17: Quiet-to-active conditions are expected for the remainder of the day.
  • December 18: Unsettled-to-active conditions are possible as fast solar wind from a coronal hole begins to influence Earth’s magnetic field. There’s a chance of reaching G1 (minor) geomagnetic storm levels late in the day, with Kp potentially reaching 5 and brief auroral activity possible.
  • December 19: Conditions are expected to trend back toward quiet to unsettled as solar wind effects weaken.

Sun news December 16: A giant coronal hole fires fast solar wind our way

(11 UTC December 15 – 11 UTC December 16)

A large coronal hole is now directing its fast solar wind toward Earth. This impressive coronal hole has an inverted “U” shape, with a prominent vertical portion that stretches from the northern hemisphere through the solar equator and deep into the southern hemisphere. It nearly connects with a smaller southern coronal hole. Coronal holes are less dense, cooler areas in the sun’s outer atmosphere, where open magnetic field lines let fast solar wind escape into space. And NOAA forecasters expect the leading edge of this fast solar wind stream to begin arriving at Earth by December 17. So it could potentially up to G1 (minor) geomagnetic storms late on December 18.

In related news, new data from NASA’s Parker Solar Probe have enabled scientists to produce the first map of the outer boundary of the sun’s atmosphere, where solar wind escapes into space. This boundary, known as the Alfvén surface, is a point of no return. It’s where solar material becomes fast enough to break free of the sun’s magnetic grasp. The researchers found that this surface becomes more structured and extended during solar maximum. Read more here.

• Flare activity: Solar activity remains at low levels, with only C-class (common) and B-class (weak) flares observed over the past day. A total of 11 flares were recorded during the past 24 hours: six C-class and five B-class events.
  • Strongest flare: A C4.0 flare from AR4304 at 17:28 UTC on December 15.
  • Other notable flares:
    • C1.3 from AR4308 at 12:05 UTC on December 15
    • C2.0 from AR4304 at 12:25 UTC on December 15
    • C1.3 from AR4307 at 23:36 UTC on December 15
    • C1.4 from AR4310 at 9:21 UTC on December 16
    • C3.0 from an unnumbered active region at 03:02 UTC on December 16
  • Sub-C flares and background: A series of upper B-class flares (B6.5–B9.4) from AR4307 and AR4310 filled the quieter intervals between C-class events.
  • Lead flare producer: AR4307 led flare activity with four total flares (one C-class and three B-class).
• Sunspot regions: The Earth-facing solar disk currently shows four numbered active regions.
  • AR4307 (beta): Showed slight growth and ranked as the most active region of the period.
  • AR4304: Continued to decay and is now classified as plage.
  • AR4309: Quickly decayed to plage shortly after being numbered.
  • AR4308 (beta): Continued to decay.
  • AR4305 (alpha): Remained stable with no flare production.
  • A newcomer, AR4310, emerged in the southwest quadrant during the period.
• Blasts from the sun? Experts did not detect any Earth-directed coronal mass ejections (CMEs) over the past day.
• Solar wind: Solar wind speeds gradually increased from about 440 km/s to a peak near 615 km/s at 6 UTC on December 16, before easing slightly to 599 km/s by 10 UTC. The total interplanetary magnetic field (IMF) strength remained steady near 8 nT. The north–south component, Bz, stayed northward throughout the period, a configuration that effectively limits energy transfer into Earth’s magnetosphere and suppresses auroral activity.
• Earth’s magnetic field: Geomagnetic conditions ranged from quiet to unsettled (Kp 1–3). At the time of writing, Kp remains at 2.

Sun news December 15: Impressive filament eruption this morning

(11 UTC December 14 – 11 UTC December 15)

A powerful filament eruption billowed from the sun’s southwest horizon in the early hours of this morning (December 15). It fired a burst of solar material and magnetic fields – a coronal mass ejection (CME) – into space. But this CME isn’t expected to impact Earth. Otherwise, the sun kept up a modest but steady pace over the past day, firing off a sequence of small C-class (common) flares. But our star remains restless. Forecasters are keeping a watchful eye on sunspot group AR4307 and nearby regions, which retain enough magnetic complexity to produce M-class (moderate) flares in the days ahead.

• Flare activity: Solar activity remained at low to moderate levels, with 10 flares recorded in the past 24 hours: 6 Cs and 4 high Bs (weak).
  • Strongest flare: C-class flare of magnitude C2.3 from AR4307 at 16:55 UTC on December 14.
  • Other notable flares:
    • C1.9 from AR4304 at 12:23 UTC on December 14 .
    • C1.0 from AR4307 at 18:04 UTC on December 14 .
    • C1.9 from AR4307 at 1:20 UTC on December 15 .
    • C1.8 from AR4304 at 1:40 UTC on December 15 .
    • C1.4 from AR4307 at 3:02 UTC on December 15.
  • Sub-C flares and background: A run of upper B-class flares (B7–B9 range) from AR4307 between about 21:35–22:27 UTC on December 14 filled in the quieter intervals between C-class events.
  • Lead flare producer: AR4307 was the dominant source region, responsible for the strongest flare (C2.3) and at least five additional B- and C-class events, indicating a persistently active but not yet explosive magnetic configuration.
• Sunspot regions: The Earth-facing solar disk showed five numbered regions in NOAA/SWPC analysis, with one new region emerging.
  • AR4307 (beta): Continued to grow and spread, with a proliferation of intermediate and trailing spots. It was the main flare producer, generating multiple C-class events including the C2.3 and frequent B-class flares. Its evolving structure and size keep it a key candidate for any future M-class flares.
  • AR4304 (beta): Produced at least two modest C-class flares (C1.9 and C1.8). Its magnetic configuration remained relatively simple, supporting low-level activity but with a lower probability for stronger events compared with AR4307.
  • AR4309 (beta): Newly numbered in this period, this small spot group emerged near the longitude of AR4307. It remained magnetically simple and did not contribute significant flaring.
  • AR4306 and AR4308: These smaller, more stable regions showed limited evolution and only minor or no flaring, behaving largely as background contributors to the disk’s overall complexity.
  • The remainder of the visible disk consisted of quiet areas and decayed plage, with one complex region (formerly AR4296) having rotated off the west limb earlier, removing a previous source of higher flare potential from view.
• Blasts from the sun? No Earth-directed coronal mass ejections (CMEs) were observed during the period.
• Solar wind: The solar wind remained elevated. But it showed a clear weakening trend as Earth continued to exit a coronal hole high-speed stream.
  Speeds decreased from around 650 km/s at the start of the period to a more sustained ~500 km/s after about 18:00 UTC on December 14. The total strength of the interplanetary magnetic field (IMF) (B_t) hovered near background levels. The crucial north–south component, Bz, stayed mostly neutral or northward through this reporting window. A northward Bz tends to close Earth’s magnetic “door,” limiting the entry of solar wind energy and thus keeping auroral activity subdued.
• Earth’s magnetic field: Earth’s magnetic field remained mostly quiet under the waning influence of the high-speed stream. Global geomagnetic conditions were primarily in the quiet-to-unsettled range, with Kp generally at 1–3.

The sun in recent days

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We sometimes feature sun images obtained using hydrogen-alpha filters. Read why.

Bottom line: Sun news December 17: A powerful far-side solar explosion sent a towering prominence over the sun’s northeast limb this morning, suggesting active regions may soon rotate into view.

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