The strongest solar flare since 2017

NASA's Solar Dynamics Observatory captured this image of a solar flare — as seen in the bright flash at far left — on December 31, 2023. The image shows a subset of intense ultraviolet light that highlights the very hot material in the flares, which is colored. In yellow and orange. Source: NASA/SDO

The Sun unleashed a powerful solar flare, peaking at 4:55 p.m ESTon December 31, 2023. NASAThe Solar Dynamics Observatory, which constantly monitors the Sun, captured an image of this event.

Solar flares are powerful bursts of energy. Solar flares and flares can affect radio communications, electrical power grids, and navigation signals and pose risks to spacecraft and astronauts.

This glow is rated as X5.0 glow. Class X indicates the most intense flares, while the number provides more information about their strength.

Credit: NOAA Space Weather Prediction Center

More details were provided by the National Oceanic and Atmospheric Administration's Space Weather Prediction Center:

Glow X5.0 (R3 Strong Radio Blackout) from Noah/SWPC Area 3536 occurred on 31/2155 UTC. This flare came from the same area that produced the X2.8 flare on December 14, 2023. It is also the largest flare observed since September 10, 2017 when the X8.2 flare occurred. Although confidence is low, modeling of the coronal mass ejection (CME) associated with this event has identified the possibility of close impact impacts near Earth as early as January 2. A G1 (minor) geomagnetic storm watch valid on January 2 was established in response.

Coronal mass ejections and solar flares. Image source: NASA Goddard Space Flight Center/Mary Pat Hrebek-Keith

Solar flares

Solar flares are sudden, intense bursts of radiation emitted from the surface of the Sun, often near sunspots. These flares result from the release of magnetic energy stored in the Sun's atmosphere. This energy heats solar matter to tens of millions of degrees, emitting gamma rays, X-rays and ultraviolet radiation.

Solar flares are mainly classified into three categories based on their strength: Category C, Category M, and Category X.

• Class C flashlights: These are small flares that have little impact on the ground. They are common and can occur frequently during periods of high solar activity.
• M Series Flares: These are medium-sized flares that can cause brief radio outages at the poles and minor radiation storms that could endanger astronauts.
• Class X torches: The most intense type, these flares can lead to planet-wide radio outages and long-lasting radiation storms. They are often accompanied by coronal mass ejections (CMEs), which can have significant effects on the Earth's magnetosphere and geomagnetic field.

Each category is ten times stronger than the previous category, and within each category, there is a finer scale from 1 to 9. For example, an X5 glow is five times stronger than an X1 glow.

Artist's concept image of the Earth-orbiting SDO satellite. Credit: NASA

NASA's Solar Dynamics Observatory

NASA's Solar Dynamics Observatory (SDO) is a space mission launched in February 2010 as part of the Living with a Star (LWS) program. The primary goal of SDO is to understand the Sun's influence on Earth and near-Earth space by studying the solar atmosphere on small scales of space and time and at many wavelengths simultaneously.

SDO is equipped with a suite of tools that provide feedback leading to a more complete understanding of solar dynamics:

1. Aerial Photography Association (AIA): It takes images of the solar atmosphere at multiple wavelengths to correlate surface changes with internal changes.
2. Helioptic and magnetic imaging (HMI): It studies the solar magnetic field and produces data to identify internal sources of solar fluctuations.
3. Extreme UV Contrast Experiment (EVE): Measures the sun's extreme ultraviolet radiation AccuracyThis is important for understanding the impact on the Earth's atmosphere.

By constantly monitoring the Sun, SDO helps scientists learn more about solar activity and how it affects Earth, and plays a critical role in our ability to predict space weather events.