From Arizona Daily Star via AURA: “Local astronomers watch our dangerous sun”

Association of Universities for Research in Astronomy

Temp 1

A coronal mass ejection, associated with a solar flare, blew out from just around the edge of the sun on May 1, 2013. Solar Dynamics Observatory [SDO] spacecraft, NASA

NASA Solar Dynamics Observatory

April 25, 2015
Dan Desrochers

Matt Penn is, in some ways, a solar weatherman.

Penn, an associate astronomer with the National Solar Observatory in Tucson, researches and observes sunspots and solar flares. Part of his work involves predicting when a flare might occur.

“We have this overall rough picture,” Penn said. “Sort of like meteorologists had before the Space Age.”

Penn’s challenge is to increase the ability to tell when a solar flare will happen and who will be affected, kind of like how meteorologists can predict when and where a hurricane will hit. He’s trying to do this through studying changes in the sun’s magnetic field and looking at the patterns of flares to determine when one might happen.

“What we’d like to say is at 11:15 we’re going to have a flare, and it’s going to have a CME (coronal mass ejection) of a certain size,” Penn said. “We can’t do that yet.”

That ability to predict solar events is important. In March, NASA space weather scientists warned that a coronal mass ejection could cause communication disruptions, along with auroras, as far south as Oklahoma.

The geomagnetic storm caused by this particular CME was weaker than predicted, but warning is critical. A direct hit from a large coronal mass ejection could cripple communication and power systems.

A solar flare contains two parts. The first, the solar flare itself, is a brightening where the flare emits X-rays and gamma rays. Those are just a form of electromagnetic radiation, and while they can affect people and objects in space, they don’t affect us on Earth because the atmosphere protects us.

The solar flare is followed, in 90 percent of cases, by a coronal mass ejection. That’s where things on Earth can get weird.

“Imagine like a slinky, and both ends of the slinky are rooted in the sun,” said Joe Giacalone, an astrophysicist and the assistant head of the University of Arizona’s Department of Planetary Sciences, “Then the thing continually expands out.”

The coronal mass ejection is a bunch of magnetized plasma — shot out from the sun.

“You need to have the material, the magnetic field and the plasma of the sun work its way out at high speeds and smash into the Earth,” Giacalone said. “That’s the coronal mass ejection that does that.”

When that mass hits the Earth, the Earth’s magnetic field gets shaken a little bit. That can cause beautiful images, like the Aurora Borealis, but it can also cause damage to transformers, GPS systems and communication devices. It can cause problems for banks, electric companies and TV providers. And all this can cost companies money.

“A chunk of the sun is coming off,” Giacalone said. “A big piece of mass is coming off the sun and entrained in the magnetic field.”

In 1859, one of the biggest and most famous flares caused the Carrington event, where a coronal mass ejection caused huge currents in telegraph lines and fires in telegraph offices.

More recently, a geomagnetic storm caused widespread, nine-hour blackouts in Quebec in 1989, when currents generated by a coronal mass ejection blew the circuits on the local power grid.

“Anytime you vary the magnetic field of the Earth — those variations can produce currents, and currents that primarily run through the ground,” Giacalone said.

The North American Electric Reliability Corp., an international regulatory agency, sets procedures for monitoring and responding to geomagnetic storms.

Locally, utility companies such as Tucson Electric Power Co. are more focused on power outages from Earth-based weather. TEP has a variety of methods to get its equipment up and running, spokesman Joseph Barrios said.

“Of all the things that affect our system and reliability and the service we provide to customers,” Barrios said, “solar flares aren’t at the top of our list.”

Solar flares can occur anytime but are more likely to occur when the sun is at the maximum range of its 11-year cycle of activity, as it is now.

This particular “solar max,” however, has been particularly mild, Penn said.

“It’s about half the strength in terms of the number of sun spots as the last cycle,” Penn said.

See the full article here.

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