The sun releases its strongest flare this cycle

Yesterday, the sun released a huge solar flare heading toward Earth. Don’t worry, it’s not quite as big as the 1859 Carrington event, but it’s still big enough to provide some spectacular aurora borealis viewing.

Large solar flares occur regularly. Quite literally, the sun goes through 11-year cycles of decreasing and increasing activity. Right now, the Sun is near the maximum of its cycle, so we’re seeing lots of sunspots and flares. When astronomers first studied cycles, they could only measure the number of sunspots at a given time. Solar flares were almost invisible to early telescopes.

But now, thanks to orbiting observatories like the Solar Dynamics Observatory, we can capture images of solar flares in real time. Astronomers currently classify the strength of solar flares by the intensity of the X-rays they emit, known as X-class. Categories are numbered by power level, and each category is twice as powerful as the previous one. So, for example, an X2 flare will be twice as strong as an X1 and half as strong as an X3.

This latest flare is rated X9 and is much more powerful than most solar flares. However, more powerful events have reached Earth before. In 1989, the X15 event caused a regional power outage in Quebec. In November 2003, the Sun released the X28 solar flare, most of which did not reach Earth. The Carrington event of 1859 occurred before astronomers created an X-class rating, but it is estimated that the X-class rating was approximately X45. Therefore, although this flare is huge, it does not seriously jeopardize the power infrastructure.

However, what it does offer is an aurora light show. When the charged particles released by the flare reach the Earth’s magnetosphere, many of them are captured by our magnetic field, spiral along magnetic field lines, and impact the Earth’s atmosphere at the polar regions. The impact causes a delicate and beautiful light show called the aurora borealis.

If you live quite far from the equator, you may be able to see them within a few days. Check out the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center to learn about the possibilities.