Facts About Solar Activity
Published October 4, 2026 · FactsSeeker
Solar activity is the changing behavior of the Sun as it releases energy, particles, and magnetic influence into space. It includes visible features such as sunspots and flares, large eruptions, and the broader space weather that can affect technology near Earth.
The Sun is dynamic, not just a steady light source
From Earth, the Sun may look like a constant source of light and heat, but NASA describes it as a changing star that sends energy into space. The study of the Sun and its influence through the solar system is called heliophysics, so solar activity includes both events on the Sun and their effects beyond it. [1]
Solar activity happens in atmospheric layers above a non-solid surface
The Sun is plasma, not a solid body, and the visible photosphere is the layer people commonly call its surface. Above it are the chromosphere, transition zone, and corona, and NASA places features such as sunspots, coronal holes, and solar flares in the Sun’s atmosphere. [1]
Different parts of the Sun rotate at different rates
Measuring a solar day is complicated because the Sun’s plasma does not rotate as one rigid object. At the equator, the Sun completes a rotation in 25 Earth days, while at the poles it takes 36 Earth days, creating different motion across the star. [1]
The solar cycle is tied to magnetic polarity changes
NASA says the Sun moves through phases of low and high activity known as the solar cycle. Approximately every 11 years, the Sun’s geographic poles change magnetic polarity, meaning the north and south magnetic poles swap. [1]
Solar maximum is the active peak of the cycle
Solar maximum is the part of the cycle when solar storm activity is greatly increased. For Solar Cycle 25, NASA says the cycle began at solar minimum in December 2019, and scientists expected activity to rise toward a predicted maximum in July 2025. [1]
Sunspots are cooler magnetic regions, not holes
Sunspots can look like dark holes, but NASA identifies them as areas slightly cooler than the surrounding photosphere. They form where parts of the Sun’s magnetic field poke into the solar atmosphere, can last from days to months, and range from 1,000 to 100,000 miles in size. [1]
Solar flares are bursts powered by magnetic energy
Solar flares are energetic bursts of light and particles triggered by the release of magnetic energy on the Sun. NASA compares their energy releases to billions of hydrogen bombs, showing why flares are important solar-activity events. [1]
Coronal mass ejections can carry magnetized particles toward Earth
Coronal mass ejections, or CMEs, are immense clouds of magnetized particles blasted outward by the Sun at over a million miles per hour. When one is directed at Earth, NASA says it can cause geomagnetic disturbances that brighten auroras and may affect satellites, power grids, or astronauts in orbit. [1]
Prominences are cooler dense material held by magnetic fields
A solar prominence is a structure of cooler, denser solar material suspended above the Sun’s surface by a strong local magnetic field. When seen against the solar disk it is called a filament, and if its magnetic structure becomes unstable it can erupt into a coronal mass ejection. [1]
Coronal holes are sources of fast solar wind streams
Coronal holes are lower-density patches in the Sun’s atmosphere that appear dark in ultraviolet views. They occur where magnetic field lines connect directly to interplanetary space, allowing solar material to escape as a high-speed stream of solar wind. [1]
The solar wind carries the Sun’s magnetic field through the solar system
The Sun’s magnetic field extends into space and is carried outward by the solar wind, a stream of electrically charged gas. This creates the heliosphere, a large magnetic bubble around the Sun that extends beyond the planets’ orbits. [1]
The corona is hotter farther from the surface, and the reason remains uncertain
NASA identifies coronal heating as one of the Sun’s major mysteries. The corona gets hotter as it stretches away from the photosphere, and the source of that heating is still described as a major unsolved puzzle in solar study. [1]
Spicules are rapid jets of solar material
At any given moment, NASA says as many as 10 million spicules can burst upward from the Sun’s surface. These plasma jets can erupt as fast as 60 miles per second and reach lengths of 6,000 miles before collapsing. [1]
Space weather is the changing near-Earth environment driven by the Sun
Solar activity helps shape space weather, which NASA compares to ever-changing weather conditions in space. Space weather can interfere with satellites, GPS, and radio communications, and it can also affect power grids and pipelines. [1]
Historical storms show that solar activity can disrupt technology
NASA describes the Carrington Event as a geomagnetic storm triggered by a solar flare observed on Sept. 1, 1859, with telegraph systems affected worldwide. Later examples include a March 13, 1989 flare linked to 6 million people losing power for 9 hours in Québec, and a December 2005 storm that disrupted satellite-to-ground communications and GPS navigation signals for about 10 minutes. [1]
Sources & further reading
Solar-cycle timing should be read as prediction rather than certainty, and layer names can vary because NASA notes that not all scientists treat the transition zone as its own region.
Sources checked 2026-09-30. Our approach to facts · Suggest a correction