AURORA WATCH: A solar wind stream is buffeting Earth's magnetic field and causing mild geomagnetic storms. High-latitude sky watchers should be alert for auroras.

ACTIVE SUNSPOT: Sunspot 960 has a "beta-gamma-delta" magnetic field that harbors energy for powerful X-class solar flares. NOAA forecasters estimate a 20% chance of an X-flare during the next 24 hours. A big eruption could trigger ion storms, radio fadeouts and, if all goes well, auroras. Amateur astronomer Alan Friedman sends this picture from his backyard in Buffalo, New York:

As the Earth icon shows, several of the sunspot's dark magnetic islands are larger than our entire planet. From end to end, the complex stretches 140,000 km, its sheer size making it an attractive target for backyard solar telescopes.

It is also a good target for shortwave radios. Sunspot 960 is crackling with M-class solar flares, and these explosions may be detected by radio listeners in two ways: (1) Solar flares sometimes produce delightfully audible radio bursts at frequencies greater than about 15 MHz. (2) The same flares can cause shortwave fadeouts at lower frequencies. For instance, an M3-flare on June 1st caused a shortwave fadeout over Europe. In the Czech Republic, Mirek Najman captured the event in this plot of a fading 3.5 MHz radio beacon.

more images: from Dennis Simmons of Brisbane, Qld, Australia;
from Robert Arnold of Isle of Skye, Scotland; from Pavol Rapavy of Rimavska Sobota,Slovakia; from Pete Lawrence of Selsey, UK; from artist Mark Seibold of Troutdale, Oregon;

HEAVENLY HALO: "It's not just the surface of the sun that's active today," reports Andrew Greenwood of Kerridge, England. The sky around the sun is pretty lively, too:

Photo details: Nikon D50, f22, 200 ISO, 1/1250

"This has to be the most wonderful ice halo display I have ever seen," says Greenwood. "I couldn't stop taking pictures: #1, #2, #3, #4."

Ice halos are rings around the sun caused by ice crystals floating in high clouds. They're visible even on hot days, because clouds 5 to 10 km high, where these halos form, are freezing cold even at the peak of summer. Put your hand in front of the sun and look around, you might catch one!

Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach.