FARSIDE SOLAR ACTIVITY: Solar activity has been very low for more than two weeks. A change could be in the offing. During the early hours of August 3rd, a new active region on the farside of the sun announced itself with a bright CME. The Solar and Heliospheric Observatory (SOHO) recorded the eruption:
The CME is not heading for Earth. It is billowing away from the sun’s farside, well off the sun-Earth line.
What’s next? Because the blast site is hidden behind the sun’s limb, we cannot yet inspect it and assess its potential for future eruptions. However, it should rotate into view in the days ahead, possibly bringing an end to two weeks of quiet.
FULL HALO CME, STORM WARNING: A coronal mass ejection (CME) is heading directly for Earth. It left the sun during the early hours of June 21st, and is expected to sweep up one or two lesser CMEs already en route, before it reaches Earth sometime on June 22nd. Click to view a movie of the “full-halo” CME, then scroll down for more discussion:
NOAA forecasters estimate a 90% chance of polar geomagnetic storms when the CME arrives. This doesn’t mean that a major space weather event is in the offing. The storm could be mild. It all depends on how the magnetic field of the CME connects to the magnetic field of Earth at the time of impact. According to NOAA, there’s only a 10% chance of nothing happening, so stay tuned.
OLSTICE AURORA WATCH: On June 18th, sunspot AR2371 unleashed the strongest solar flare in nearly 2 months. The M3-class explosion caused a brief shortwave radio blackout over North America, and it hurled a CME into space. SOHO (the Solar and Heliospheric Observatory) recorded a movie of the expanding cloud:
The CME is not heading directly for Earth. Nevertheless, it is probably geoeffective. According to NOAA computer models, the CME should deliver a glancing blow to our planet’s magnetic field during the late hours of June 21st. High-latitude sky watchers should be alert for solstice auroras.
NCREASING CHANCE OF FLARES: NOAA forecasters have boosted the odds of an M-class flare today to 25%. The reasons are circled in this June 12th image from NASA’s Solar Dynamics Observatory:
Sunspots AR2367 (left) and AR2360 (right) are growing with unstable magnetic fields that harbor energy for M-class solar flares. At the moment, both active regions are crackling with low-level C-class flares. It may be just a matter of time before a more significant eruption occurs.
CHANCE OF MAGNETIC STORMS TODAY: A CME is heading in the general direction of Earth, and it could deliver a glancing blow to our planet’s magnetic field later today. Scroll past this SOHO coronagraph movie for storm probabilities:
NOAA forecasters estimate a 50% chance of polar geomagnetic storms. The cloud was hurled into space two days ago by an M9-class explosion in the magnetic canopy of sunspot AR2242. Although the bulk of the CME flew south of the sun-Earth line, a collision is still possible. Computer models suggest a glancing impact on Dec. 19th with magnetic reverberations lasting until the 20th. High-latitude sky watchers should be alert for auroras.
SUPER-SUNSPOT PREPARES TO DEPART: The biggest sunspot in nearly 25 years is about to leave the solar disk. This picture from Sergio Castillo of Corona CA shows AR2192 approaching the western limb on Oct. 27th:
“For its final trick, AR2192 is going to treat us by mimicking a Giant Skull,” says Castillo, one of many readers who has noted the resemblance between the sunspot and a skeletal face. “Say Happy Halloween as it gets ready to turn away from us. “
As AR2192 approaches the sun’s horizon, it is no longer facing Earth. However, the odds of an Earth-directed radiation storm are higher than ever. The reason is, the western limb of the sun is well-connected to Earth. Solar magnetic fields springing out of that region spiral back to our planet. If a sunspot passing through the area explodes, those spiralling magnetic fields can funnel energetic particles in our direction.
In only a few days, the behemoth sunspot will begin a 2-week transit of the far side of the sun, carried around by the sun’s 27-day rotation. However, that doesn’t mean we’ve seen the last of this magnificent active region. Big sunspots typically persist for two or three solar rotations before they decay. After it leaves, AR2192 will return in November.
ERUPTING FILAMENT CREATES ‘CANYON OF FIRE’, CME: A magnetic filament snaking down the middle of the solar disk erupted during the late hours of Aug. 15th. The eruption split the sun’s atmosphere, hurling a CME toward Earth and creating a “canyon of fire,” shown here in a movie recorded by the Solar Dynamics Observatory:
The glowing walls of the canyon trace the original channel where the filament was suspended by magnetic forces above the stellar surface. From end to end, the structure stretches more than 250,000 km–a real Grand Canyon.
Of greater interest to us on Earth is the coronal mass ejection (CME) which billowed away from the blast site: movie. Coronagraph images from the Solar and Heliospheric Observatory show that it is a ‘halo CME.’ In other words, it is heading straight for Earth. Minor geomagnetic storms are possible when the cloud arrives during the late hours of August 18th. High-latitude sky watchers should be alert for auroras.
ALMOST-X FLARE: Departing sunspot AR1996 erupted on March 12th at 2234 UT, producing an M9-category blast that almost crossed into X-territory. NASA’s Solar Dynamics Observatory captured the extreme ultra-violet flash:
UV radiation from the flare caused waves of ionization to ripple through Earth’s upper atmosphere. These waves briefly altered the propagation of low-frequency radio transmisions around the planet, as shown in this plot from amateur radio astronomer Jim Tegerdine of Marysville, Washington. Otherwise the flare was not geoeffective. The sunspot’s location near the sun’s eastern limb mitigated Earth effects.
The next big flare could have a greater influence on our planet. Sunspot AR2002 is directly facing Earth, and it has a ‘beta-gamma-delta’ magnetic field that harbors energy for strong explosions. NOAA forecasters estimate an 80% chance of M-class flares and a 15% chance of X-flares on March 13th
BIG SUNSPOT FACES EARTH: Colossal sunspot AR1785 is now directly facing Earth. The active region has a ‘beta-gamma-delta’ magnetic field that harbors energy for X-class flares, yet so far the sunspot has been mostly quiet. Could it be the calm before the storm? NOAA forecasters estimate a 55% chance of M-flares and a 10% chance of X-flares on July 8th.
Sprawling more than 11 Earth-diameters from end to end, AR1785 is one of the biggest sunspots of the current solar cycle. In fact, it can barely fit on the screen. Click on the dark core below to see a complete hi-res picture taken by Christian Viladrich of Nattages, France:
To take the picture, Viladrich used a filtered 14-inch Celestron telescope. All those irregular blobs surrounding the primary dark core are boiling granules of plasma as small as the state of California or Texas. It’s a very sharp picture.
M-CLASS SOLAR FLARE: Sunspot AR1778 produced an impulsive M2-class solar flare on June 23rd at 20:56 UT. NASA’s Solar Dynamics Observatory recorded the extreme ultraviolet flash:
The eruption flung material away from the blast site, but the debris does not appear to be heading toward Earth. Except for the effects of the UV flash, which created a short-lived wave of ionization in Earth’s upper atmosphere, this flare was not geo-effective.
More flares could be in the offing. In addition to AR1778, sunspots AR1775 and AR1776 have ‘beta-gamma’ magnetic fields that harbor energy for significant eruptions. NOAA forecasters estimate a 40% chance of M-flares and a 5% chance of X-flares on June 24th.