SUPER SOLAR FLARE: In September 1859, the sun unleashed a solar flare so intense that the flash of light rivaled the surface brightness of the sun itself. A ferocious geomagnetic storm ensued in which Northern Lights descended as far south as the Bahamas and Hawaii. Meanwhile, telegraph engineers disconnected their batteries and powered communications by electricity from the auroras! Could it happen again? Get the answer from Science@NASA

AMAZING PROMINENCE: Today, a massive solar prominence is delighting amateur astronomers with its rapid mutations. "I've seen lots of prominences in my time, but this one is totally amazing," reports Pete Lawrence of Selsey, UK. "Each half-hour shot I took of it recorded large structural changes." One photo, he insists, looks like a War of the Worlds martian. "That's the best part of solar astronomy, it's never the same," adds Greg Piepol of Rockville, Maryland. Readers, if you have a solar telescope, look now!
 

Filaments are clouds of hydrogen held above the surface of the sun by magnetic fields. Backlit by the inferno below, they appear dark and cool, but that is an illusion. Like all things solar, filamentary clouds are bright and red-hot. We see this most clearly when a filament juts into the black of space beyond the sun's edge, as this one is doing in the left half of the photo.

In fact, this filament is about to go all the way over the edge, reclassifying itself from filament to prominence. If you have a solar telescope, train it on the western limb of the sun and watch the metamorphasis.

more images: from James Kevin Ty of Manila, the Philippines; from E. Signorelli and J. Stetson of South Portland, Maine; from Peter Paice of Belfast, Northern Ireland; from Malcolm Park of London, England, UK; from Maxim Usatov of Prague, the Czech Republic;  

MUST-SEE FILAMENT: A dark magnetic filament is snaking over the sun's western limb today, producing a beautiful 3D scene for amateur astronomers to photograph. "It's spectacular," says Robert Arnold who sends this picture from the Isle of Sky, Scotland. If you have a solar telescope, take a look!

That's what we mean by "quiet sun."

more images: from P-M Hedén of Vallentuna, Sweden; from Patricia Cannaerts of Belgium; from Peter Paice of Belfast, Northern Ireland; from Monty Leventhal of Sydney. Australia;

CME UPDATE: Geomagnetic activity remains low. A coronal mass ejection hurled into space by the April 26th "no-sunspot" solar flare has either missed Earth or its impact was too weak to register on solar wind sensors in Earth orbit. Auroras tonight appear unlikely.

SOLAR BLAST: No sunspots? No problem. On April 26th the blank sun unleashed a solar flare without the usual aid of a sunspot. At 1408 UT, Earth-orbiting satellites detected a surge of X-rays registering B3.8 on the Richter scale of solar flares. Shortly thereafter, SOHO coronagraphs recorded a coronal mass ejection (CME) billowing away from the sun:

The expanding cloud could deliver a glancing blow to Earth's magnetic field late on April 28th or 29th. High-latitude sky watchers should be alert for auroras when it arrives.

This strange solar flare came from a patch of sun (N08,E08) where magnetic fields were not intense enough to form a visible sunspot (sunspots are made of magnetism). Nevertheless, magnetic fields were present with sufficient energy and instability to produce a powerful explosion. NASA's twin STEREO spacecraft, observing the sun from widely separated vantage points, recorded a million mph shock wave or "solar tsunami" spreading from the blast site through the sun's atmosphere: movie.

KENT STEADMAN - REST IN PEACE