Active aurora likely to be seen in Juneau this week

Six-minute combined night exposure of Mendenhall Glacier and Mendenhall Lake on Nov. 9, 2013. (Photo by Matt Miller/KTOO)

Juneau residents may be in for a visual treat this week. Expect to see displays of the aurora borealis — or northern lights — because of the sun’s activity and a rare Southeast Alaska weather forecast for clear skies overnight.

How is the aurora created? Think of a neon light. When you plug it in, the electricity excites the gases inside the tube.

“They really are the same processes that happen in the neon sign are happening in the aurora. Aurora is just bigger,” says Donald Hampton, a research associate professor at the University of Alaska Fairbanks’ Geophysical Institute.

Charged particles from the sun collide with the earth’s atmosphere and create the green — and sometimes red and white — patterns that dance across the sky.

“What we have right now is what’s called a coronal hole. And what comes out of that is usually a stream of sort of faster particles,” Hampton explains. “It’s called a high-speed stream fairly often. That’s usually fairly stationary on the sun.”

“And, of course, the sun rotates every 27 days. So, we’re kind of expecting the same thing to happen here at the end of October,” says Hampton. “And that’s why the forecast is showing some pretty good signs for aurora.”

Hampton says it’s difficult to predict how long the display will last, how intense it will be, or where it will be visible. But he says it’ll likely last several days and be visible overhead to Anchorage residents.

Juneau residents should look to the northern horizon after 10 o’clock at night.


Related resources and web links:

UAF Geophysical Institute’s aurora forecast
Poker Flat Allsky Aurora Camera
Aurorasaurus – Reporting Auroras from the Ground Up
NOAA Space Weather Prediction Center