SDO Solar Flare on March 7 2012
SDO Solar Flare--the bright spot on the left--on March 7 2012. Credit: NASA/SDO

The first X-Class solar flare of the year went off on March 7th in spectacular fashion. Fortunately the flare went off where it’s supposed to: on the Sun. Had this intense magneto-plasmic explosion gone off on Earth, we’d be toast; one of these releases an amount of energy on the order of 100 billion megatons of TNT.

Solar flares are highly energetic bursts of energy ignited by magnetically active regions on the Sun. Magnetic fields, generated by the motion of the Sun’s hot, electrically charged gases, cause many of the Sun’s more showy features, including the blemish familiar to most, the sunspot.

And yesterday, that’s exactly what we saw from Chabot’s observatory deck: a sunspot…and we didn’t even need a telescope to see it! Let me explain. The active region that produced the powerful X-class flare only hours earlier left its mark on the Sun’s bright complexion with a large cluster of sunspots—such an expansive cluster that it could be seen with the “naked eye.”

Now, when I say naked eye, in this case I don’t mean we were encouraging our visitors (mostly school kids at the time) to stare at the Sun directly. That would be pointless since the Sun is so bright at midday that it blinds us to any features we might see (and could blind us permanently if we look too long, even with sunglasses).

So, we have the kids look at the Sun through pieces of welder’s goggle glass #14. It’s a very dark filter—so dark that you pretty much can’t see anything other than the Sun, or a welding torch, through it. This Sun-looking glass lets us peer safely into that wonderland in the sky, the solar disk, which ordinarily averts our attention by sheer brilliance.

Through the glass the Sun becomes a greenish disk, the same apparent size as the Moon. Most of the time, that’s all we see: a glowing green disk in a sky of blackness. But even that is actually pretty awesome, and the sight routinely catches people by surprise.

Yesterday, however, the sunspot cluster marking the active region that produced the X-class flare was easily seen, unmagnified: a little dark spot on the Sun. And our eyes didn’t even sting.

Now, a day after the flare, Earth is in the midst of a blast of plasma that was triggered by the flare activity, and a geomagnetic storm is in progress: the impact of an enormous bubble of plasma (electrically charged gas) that was blown in our direction has clobbered Earth’s deflector screen, aka its global magnetic field.

Though the effects of a solar blast like this one and the geomagnetic storm it can produce usually go unnoticed by most, the event can cross over into our lives, if severe enough. Interference in telecommunications from atmospheric disturbance and even the rare power blackout caused by a magnetically induced overload of a power grid, have happened.

In space, satellites have been damaged by these storms, and astronauts on the space station generally take cover and wait them out. And closer to Earth’s poles, lucky residents may be treated to a bright display of the Aurora—the Northern and Southern lights—as auroras are powered by solar activity.

We should expect more strong flares over the next year or so as the Sun proceeds through the peak in its current activity cycle, expected to climax sometime in 2013. I fully expect to view more “naked-but-protected-eye” sunspots, and to enjoy plenty of colorful movies of solar activity from NASA’s Solar Dynamics Observatory (now on display in Chabot’s telescope domes). Drop by Chabot on a sunny day and we’ll put spots in your eyes.

  • I8lutfisk

    Never, never, never look directly at the Sun with any kind of filter! I damaged my retina looking at sun-spots with a sun-filter on my telescope. The ophthalmologists that examined me said that the Central Serous Retinopathy that resulted is common amongst welders. They strongly admonished me to never look directly at the Sun with any device, but only indirectly view it by projecting its image onto a surface. You are being very irresponsible with your student’s vision.

  • Gabriel Roybal

    we need to get some sort of KQED alert system to make sure we don’t miss any of these events!


Ben Burress

Benjamin Burress has been a staff astronomer at Chabot Space & Science Center since July 1999. He graduated from Sonoma State University in 1985 with a bachelor’s degree in physics (and minor in astronomy), after which he signed on for a two-year stint in the Peace Corps, where he taught physics and mathematics in the African nation of Cameroon. From 1989-96 he served on the crew of NASA’s Kuiper Airborne Observatory at Ames Research Center in Mountain View, CA. From 1996-99, he was Head Observer at the Naval Prototype Optical Interferometer program at Lowell Observatory in Flagstaff, AZ. Read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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