How Sunspots Work

By: Patrick J. Kiger  | 

Sunspots' Effect on Earth

Sunspots are connected with other solar events like flares and coronal mass ejections (CMEs). A solar flare is a sudden release of energy from the sun, while a CME actually shoots hot plasma from the sun into space. The precise mechanisms that trigger flares and CMEs are not yet known, but the bigger the group of sunspots, the more intense such solar weather tends to be. Flares and CMEs can send enormous amounts of energy and charged particles hurtling into collision with the Earth's atmosphere, where they can cause magnetic storms that disrupt or alter radio and cell phone communication and can wreak havoc with electrical grids. During the 1989 solar max, for example, a power surge triggered by solar energy damaged transformers that were part of the Hydro-Quebec power system. That surge left 6 million people in Canada and the northeastern U.S. without electricity for more than nine hours. Oddly, sunspot activity actually can help ham radio reception because the increased radiation causes the atmosphere to bend higher radio frequencies back toward Earth.

The increase in radiation that accompanies a solar flare is a theoretical health hazard to spacewalking astronauts, crew and passengers in high-flying aircraft, but there isn't any evidence that people have actually gotten sick from such exposure.


It's unclear if there's a link between solar weather and changes in the Earth's climate, because our planet's climate is influenced by so many other factors -- from volcanic eruptions to man-made emissions of greenhouse gases. The Maunder minimum in the 1600s and 1700s, when there was almost no sunspot activity, coincided with a period of cold temperatures and severe winters in Europe and North America. However, scientists haven't been able to determine if the two phenomena were actually related, though they think that a decrease in the sun's ultraviolet emissions may have triggered the change in climate.

UFO watchers and paranormal enthusiasts also see links between the unknown and increased sunspot activity, but there may be more of a correlation with the intensity of a person's belief in mystical phenomena.

Next, we'll explore how astronomers studied sunspots and developed theories about them.

Sunspots FAQ

What causes a sunspot?
Sunspots occur because the interior and exterior of the sun rotate separately; the outside rotates more quickly at the equator than at the solar north and south poles. Over time, that uneven movement twists and distorts the sun's main magnetic field. This creates spots that have so much magnetic power that they push back the hot gases beneath them and prevent the heat from rising directly to the surface, creating sunspots.
What is the frequency of the sunspot cycle?
Roughly every 11 years, the number of sunspots increases from nearly zero to more than 100 and then decreases to near zero again as a new cycle starts. This pattern is called the sunspot cycle.
What causes the sunspot cycle?
The sunspot cycle occurs because the sun contains a sort of conveyor belt that circulates a hot, electrified gas called plasma between the sun's equator and its poles and then back again over a period of years.
Do sunspots affect climate?
It's unclear if there's a link between solar weather and changes in Earth's climate because our planet's climate is influenced by so many other factors, from volcanic eruptions to man-made emissions of greenhouse gases.
How long does a sunspot last?
An individual sunspot can last anywhere from a few days to a few months.