It appears that not even the sun is up to celebrate New Year’s Eve with some fireworks. The biggest solar explosion to be seen since 2017 occurred at the end of 2023 when satellites close to Earth saw a massive X5-class solar flare erupting from our star in the final hours of the year.

The coronal mass ejection (CME), a massive blob of solar particles traveling at high speed that accompanied the flare, is predicted by the National Oceanic and Atmospheric Administration (NOAA) to brush Earth’s magnetic field today (Jan. 2) and may cause minor geomagnetic storms and widespread auroras across the sky. The best places to see auroras are usually close to Earth’s poles, but CMEs have the ability to push auroras much lower in latitude than they usually are.

When the sun’s magnetic fields get too tangled, they burst like rubber bands, sending strong radiation waves hurtling through space at a high rate of speed. This is known as a solar flare. The strongest kind of solar flares are called X-class flares, and when their concomitant radiation bursts cross Earth, they have the potential to disrupt power grids, radio stations, and satellites.

The Dec. 31 X5 flare was the strongest of 2023, easily outperforming the massive Dec. 14 X2.8 flare that originated from the exact same location on the sun. According to NOAA, that X2.8 flare was also deemed to be the most potent flare since a massive X8.2-class flare that burst from the sun on September 10, 2017.

The flare that occurred on New Year’s Eve was also the strongest of solar cycle 25, which started in 2019 and is expected to peak this year. The sun has an 11-year cycle of activity that peaks roughly halfway through, known as the solar maximum. The peak of the current cycle was originally anticipated to occur in 2025 and to be relatively mild; however, scientists have revised their predictions due to a surge in solar activity in 2023.

It is currently anticipated that solar maximum will occur in 2024. The peak will be strong, if last year’s intense solar activity is any guide. In addition to these strong flares, 2023 saw the strongest geomagnetic storm in 20 years and the highest monthly number of sunspot observations in 20 years.