FARSIDE ERUPTION: An active region located just behind the sun’s northeastern limb erupted this morning, producing an X-ray flash that registered M1.5 on the Richter Scale of Solar Flares — despite the fact that it was partially eclipsed by the edge of the sun. The true intensity of the flare was much greater, possibly X-class. The explosion also hurled a spectacular CME into space:
Type II radio emissions from the expanding cloud suggest an expansion velocity of at least 510 km/s (1.1 million mph). That’s a typical speed for CMEs.
Within a few days, the sunspot responsible for this outburst will rotate around to the Earthside of the sun. At that time, Earth-directed solar activity could increase. August and September were quiet months, but in October the sun seems to be waking up
CORONAL HOLE: NASA’s Solar Dynamics Observatory is monitoring a coronal hole in the sun’s northern hemisphere. It is the UV-dark region in this image taken during the early hours of Sept. 21st:
The white lines in the image trace the sun’s magnetic field. A coronal hole is a place where the magnetic field spreads apart, allowing solar wind to escape. A stream of solar wind flowing from this particular coronal hole is heading for Earth, due to arrive on Sept. 23-24. Its arrival could add to the impact of a minor CME expected to reach Earth at about the same time. Polar geomagnetic storms are possible early next week.
ANOTHER SUNDIVING COMET: Here we go again. Another comet is diving into the sun, the second one this week. Coronagraphs onboard the Solar and Heliospheric Observatory (SOHO) are monitoring the death plunge:
The icy comet, which probably measures a few 10s of meters wide, is vaporizing furiously and is not expected to survive much longer.
Like the comet that came before it, this one is a member of the Kreutz family. Kreutz sungrazers are fragments from the breakup of a single giant comet many centuries ago. They get their name from 19th century German astronomer Heinrich Kreutz, who studied them in detail.
Because of their common parentage, sungrazers often come in clusters. After today’s sungrazer evaporates, it wouldn’t be surprising to find yet another in the offing.
CORONAL HOLE: A coronal hole has formed in the sun’s northern hemisphere, and it is spewing solar wind into space. NASA’s Solar Dynamics Observatory photographed the UV-dark gap during the early hours of August 14th:
In the image, above, the sun’s magnetic field is traced by white curving lines. The coronal hole is where those magnetic field lines have opened up, allowing solar wind to escape. A stream of solar wind flowing from this coronal hole is expected to reach Earth on August 16-18. NOAA forecasters estimate a 25% chance of polar geomagnetic storms when the windy stream arrives.
BREAK IN THE QUIET: Solar activity has been low for weeks. The emergence of sunspots AR1817 and AR1818 could break the quiet. Both pose a threat for M-class solar flares. AR1817 has already produced one almost-M class eruption:
The C8-category flare was recorded by NASA’s Solar Dynamics Observatory on August 11th at 2158 UT. Whether it is a herald of bigger things to come remains to be seen. AR1817 is almost directly facing Earth, so any eruptions this week will probably be geoeffective.
CHANCE OF STORMS: NOAA forecastesrs estimate a 65% chance of polar geomagnetic storms on August 10th when one and perhaps two CMEs are expected to hit Earth’s magnetic field. The incoming clouds were propelled from the sun by a flurry of erupting magnetic filaments on Aug. 6-7. High-latitude sky watchers should be alert for auroras.
A space telescope aimed at the sun has spotted a gigantic hole in the solar atmosphere — a dark spot that covers nearly a quarter of our closest star, spewing solar material and gas into space.
The so-called coronal hole over the sun’s north pole came into view between July 13 and 18 and was observed by the Solar and Heliospheric Observatory, or SOHO. NASA released a video of the sun hole as seen by the SOHO spacecraft, showing the region as a vast dark spot surrounded by solar activity.
Coronal holes are darker, cooler regions of the sun’s atmosphere, or corona, containing little solar material. In these gaps, magnetic field lines whip out into the solar wind rather than looping back to the sun’s surface. Coronal holes can affect space weather, as they send solar particles streaming off the sun about three times faster than the slower wind unleashed elsewhere from the sun’s atmosphere, according to a description from NASA.
“While it’s unclear what causes coronal holes, they correlate to areas on the sun where magnetic fields soar up and away, failing to loop back down to the surface, as they do elsewhere,” NASA’s Karen Fox at the agency’s Goddard Space Flight Center in Greenbelt, Md., explained in an image description.
These holes are not uncommon, but their frequency changes with the solar activity cycle. The sun is currently reaching its 11-year peak in activity, known as the solar maximum. Around the time of this peak, the sun’s poles switch their magnetism. The number of coronal holes typically decreases leading up to the switch.
After the reversal, new coronal holes appear near the poles. Then as the sun approaches the solar minimum again, the holes creep closer to the equator, growing in both size and number, according to NASA.
The $1.27-billion (1 billion euros) SOHO satellite was launched in 1995 and is flying a joint mission between NASA and the European Space Agency (ESA). It watches solar activity from an orbit about the Lagrange Point 1, a gravitationally stable spot between Earth and the sun that is about 932,000 miles (1.5 million kilometers) from our planet.
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.
RADIATION STORM: A minor solar proton storm is underway around Earth. Registering “S1” on NOAA storm scales, the storm is not yet intense enough to have a significant effect on satellites or air travelers. It is, however, trending upward, so the situation could change.
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.
