Sunspot that produced aurora display in early May re-emerges

A sunspot region designated as AR3697 has re-emerged from the far side of the sun. The area has generated a solar flare forecasted to bring moderate geomagnetic storm conditions Friday. That forecast comes from the Space Weather Prediction Center branch of the National Oceanographic and Atmospheric Administration.

David Hoskin 3697 The active sunspot 3697 emerging from the far side of the sun. (Source: David Hoskin, Professor Emeritus Dalhousie University)

While not forecasted to match the severe geomagnetic storm that brought a spectacular aurora display to the Maritimes and large portions of North America early this month, it may bring some glimpses. The Space Weather Prediction Centre notes the aurora may become visible for the U.S. from New York to Idaho on Friday. That could make it a close call for the Maritimes as well.

A measurement of planetary geomagnetic activity is given as the Kp index ranging from zero to nine. A Kp index near six is forecasted and has been associated with spotting the aurora in parts of the Maritimes. Currently the timing of that peak index isn’t perfect for aurora viewing, reaching peak Friday afternoon. Should the flare impact later or the geomagnetic activity remain high enough into the night, spotting the aurora could still be possible.

Kp index A Kp index of 6 or higher has sometimes allowed for glimpses of the aurora in the Maritimes. (Source: CTV News Atlantic)

Northern areas of the Maritimes would be most favoured and any display of the aurora would likely be faint and low to the northern horizon. The usual night sky viewing conditions apply, such as getting away from city lights and finding as best an unobstructed view of the northern horizon as possible. There are numerous sites to monitor the geomagnetic and aurora forecasted, including the Space Weather Prediction Center: https://www.swpc.noaa.gov/ and University of Alaska: https://www.gi.alaska.edu/monitors/aurora-forecast.

Early May aurora

An interesting note about region AR3697. Before it rotated around the sun it was previously designated as AR3664. That makes it the same spot or region on the sun that produced the solar flare that led to a severe geomagnetic storm earlier this month. It was that storm that allowed the Maritimes to observe the aurora overhead.

David Hoskin 3664 A picture of the same area, then designated as 3664, earlier this month. The sunspot producing the solar flare that created the spectacular aurora display in early May. (Source: David Hoskin)

The activity forecasted for Friday into Saturday isn’t nearly as strong as that event. If the aurora does show Friday night it would most likely be fainter and closer to the northern horizon.

Night sky viewing conditions for the Maritimes Friday night are generally favourable. Patchy cloud and cool, but not expected to be overcast or rainy.