On Oct. 28, 2021, NCEI scientists out of CIRES observed a strong solar flare via the Solar Ultraviolet Imager (SUVI) on the GOES East satellite at 11:35 am ET. The flare produced aurora (northern lights) that were visible across Canada and as far south as Pennsylvania, Iowa, and Oregon. The JPSS satellites were able to capture imagery of these aurora via their VIIRS instrument, showing their extent.
Solar flares—an important type of space weather—are localized, explosive outbursts on the Sun, and can generate intense radiation in the form of X-rays and energetic particles that can sometimes affect Earth. Because this radiation often travels at or near the speed of light, it can reach the Earth within about 8 minutes. Flares are often linked to eruptions, called coronal mass ejections (CMEs), which hurl massive clouds of magnetized plasma far into space, plowing right through the continuous flow of charged particles that normally stream from the Sun, called solar wind, and can reach Earth in up to three days.
Luckily, the Earth has a magnetic field that surrounds us like a protective bubble, deflecting most of this harmful radiation. The Sun, which is made of electrified gases called plasma, also generates its own magnetic field, and all solar activity is driven by these magnetic fields.
We can see manifestations of the Sun's magnetic field in the form of active regions, which appear at the Sun’s surface as cooler, dark areas, and in SUVI observations of the Sun’s corona as bright concentrations of loops. Active regions mark areas where magnetism is the strongest. Strong solar flares are powered by the energy stored in the magnetic fields of these active regions.
Sunspots are used as an indicator of solar activity, and the number and location of sunspots is used to track the Sun's overall activity. Although the Sun may look like a constant ball of light every day, it actually goes through a cycle of increasing and decreasing activity that lasts around 11 years.
Researchers determined that the solar minimum occurred in Dec. of 2019, meaning the Sun’s activity is beginning to ramp up and should peak around 2025, increasing the chance for stronger solar storms in the coming years. Afterward, geomagnetic activity will begin to decrease again and a new cycle will begin.
Increased radiation and associated geomagnetic storms can potentially affect power grids on Earth as well as radio signals and communications systems. They can also affect our satellite operations and GPS navigation capabilities. Additionally, astronauts in space have to be extra careful, particularly if they are doing a spacewalk. Outside of the Earth's protective atmosphere, the extra radiation they are exposed to may cause radiation poisoning or other harmful health effects.
NOAA satellites help monitor the activity of the Sun and when solar flares, or coronal mass ejections occur. Since these events can happen unpredictably and some can reach Earth within minutes, NOAA's Space Weather Prediction Center uses this information to monitor the activity on the Sun and makes forecasts, predictions, and alerts.
To help with this, the GOES satellites also house the Extreme Ultraviolet and X-ray Irradiance Sensors (EXIS), which monitor the Sun’s electromagnetic radiation and serve as a critical first warning system for the onset of flares, the Space Environmental In-Situ Suite (SEISS), which helps assess the electrostatic discharge risk and radiation hazards to astronauts and satellites, and a Magnetometer, which measures the Earth’s magnetic field.
As the solar cycle moves toward the solar maximum, NOAA satellites will continue to monitor the Sun’s activity.