A spectacular natural event could light up the skies this weekend as a colossal butterfly-shaped coronal hole has opened in the Sun’s atmosphere. Space weather forecasters say this striking feature, stretching about 310,000 miles (500,000 kilometers) across, is releasing a fast-moving stream of solar wind directly toward Earth. The solar wind is expected to arrive around September 13–14, potentially triggering a geomagnetic storm and dazzling displays of auroras.
What Is Happening?
Coronal holes are regions on the Sun where magnetic field lines open outward, allowing streams of charged particles to escape into space. These areas appear darker in extreme ultraviolet images of the Sun and often release high-speed solar wind. When this wind reaches Earth, it can interact with our planet’s magnetic field, creating disturbances known as geomagnetic storms.
In this case, the coronal hole’s size and distinctive butterfly shape have caught the attention of both scientists and sky watchers. As the solar wind hits Earth, it has the potential to energize particles in our upper atmosphere, leading to vivid auroras commonly called the northern and southern lights.
Forecast and Storm Strength:
According to the U.K. Met Office, the incoming solar wind stream could produce geomagnetic conditions ranging from active to G1 (minor) storm levels, with a possibility of reaching G2 (moderate) levels between September 13 and 14. The U.S. National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center has given a slightly more cautious forecast, expecting mainly G1 activity but noting that stronger conditions could develop if the solar wind’s embedded magnetic field aligns favorably with Earth’s.
Geomagnetic storms are ranked on a scale from G1 (minor) to G5 (extreme). Even minor storms can create auroras visible at high latitudes, while moderate to strong storms may extend visibility farther south into mid-latitude regions.
What Are Auroras?
Auroras are one of nature’s most beautiful light shows. They occur when charged particles from the Sun collide with gases in Earth’s atmosphere, such as oxygen and nitrogen. These collisions transfer energy to the gases, which is then released as colorful light. Green and red auroras are caused by oxygen, while purple and blue hues are linked to nitrogen.
During strong geomagnetic storms, auroras can appear more dynamic and widespread, sometimes stretching far beyond the polar regions. For skywatchers, this weekend could be an opportunity to witness these stunning natural lights if conditions are favorable.
Where and When to Look:
The best chance to see auroras will be in high-latitude locations such as Alaska, Canada, Iceland, Greenland, Scandinavia, and northern Russia. If the storm intensifies to G2 or stronger, auroras may become visible farther south into parts of the northern United States and central Europe. Observers should look northward under dark, clear skies, away from city lights, during the late evening and early morning hours of September 13–14.
Solar activity is increasing as the Sun approaches the peak of its 11-year cycle, known as solar maximum, expected around 2025. Events like this highlight the dynamic relationship between the Sun and Earth and remind us of the power of space weather. While this particular storm is not expected to cause major disruptions, stronger storms can impact satellites, communications, navigation systems, and even power grids.
While forecasts cannot guarantee exactly how strong the geomagnetic storm will be, the arrival of the solar wind stream is certain. For many skywatchers, this weekend offers the exciting possibility of witnessing the northern lights. Whether the storm reaches G1 or climbs to G2, the potential for auroras adds a magical element to the September night sky.
Source: U.K. Met Office, NOAA Space Weather Prediction Center, Space.com