What is space weather? Space weather is activity on the Sun that sends pulses of subatomic particles and full spectrum electromagnetic radiation to Earth. These solar storms can impact everyday technology like Global Positioning Systems (GPS), satellites, and electric power grids. Space weather is a consequence of the behavior of the Sun, the nature of Earth’s magnetic field and atmosphere, and our location in the solar system. Outbursts from huge explosions on the Sun—solar flares and corona mass ejections (CMEs)—send space weather storms hurtling outward through our solar system. The Sun also emits a continuous stream of radiation in the form of charged particles that make up the plasma of the solar wind.

A dramatic example of the effects of space weather occurred in March 1989 when a solar storm knocked out power in Quebec for up to 36 hours. The Hydro-Quebec electrical utility went from full operating capacity to blackout status in 92 seconds. Six million people were plunged into cold and darkness.

3.1.1 Features of the Sun

The Sun is a gas ball of hydrogen and helium. The Sun’s enormous mass is held together by gravity, producing immense pressure and temperature at its core. The Sun has six regions: the core, the radiative zone, and the convective zone in the interior; the visible surface, called the photosphere; the chromosphere; and the outermost region, the corona. The Sun is not featureless, but has storms much like the Earth has weather.

At the core, the temperature is about 27 million degrees Fahrenheit (15 million degrees Celsius), which is sufficient to sustain thermonuclear fusion. This is a process in which smaller atoms combine to form larger atoms and in the process release staggering amounts of energy. Specifically, in the Sun’s core, hydrogen atoms fuse to make helium. The energy manufactured is 3.8 x 10²³ kilowatts (kilojoules/sec). One second of the Sun’s energy could power the United States for 9 million years.

 

The Sun is constantly releasing subatomic particles, predominately protons and electrons, into the solar system. These particles are called the solar wind. A solar storm can release larger quantities of high energy charged particles, which are accelerated close to the speed of light. These particles may arrive at the Earth between 30 minutes and several days after leaving the Sun. These particle events and similar electromagnetic radiation bursts are associated with sunspots, solar flares and corona mass ejections (CMEs).

3D Model of the Sun

This NASA 3D model illustrates some features of the Sun.

Sun Spots

Sunspots are visible spots on the surface of the Sun that are cooler than their surrounding area (4500°C versus 5800°C). These cooler areas appears as dark spots. As the Sun rotates, sunspots on its surface appear to move from left to right. The Sun takes 27 days to make one complete rotation; whereas the Earth takes 24 hours to complete a rotation. Sunspots occur when strong magnetic fields emerge through the solar surface and allow the surrounding area to cool slightly.

Sunspot activity is not constant, but has a quasi-periodic variation of eleven years. An increase in sunspots corresponds to an increase in solar activity, such as solar flares and CMEs. Sunspots were recorded as early as 325 B.C. The sunspot cycle going back to the 1900s is shown here, with the next peak expected in 2025. (see the graph below)

 

 

Video: How to Track the Solar Cycle (6:04 min)

This NASA video describes how sunspots occur and are tracked.

 

3.1.4 Space Weather Effects

Space weather can impact seven aspects of modern society:

Electric Power

Large currents in the ionosphere can induce currents in power lines. Surges from these induced currents can cause massive network failures and permanent damage to electric grid components.

Navigation Systems

Disturbances in the ionosphere can cause degradation in GPS range measurements and in severe circumstances, loss of lock by the receiver on the GPS signal.

Aviation

Space weather storms can cause lost or degraded communications, radiation hazards to crew and passengers, unreliable navigational information, and problems with flight-critical electronic systems.

Human Space Exploration

Energetic particles present a health hazard to astronauts on space missions as well as threats to electronic systems. During space missions, astronauts outside spacecraft are less protected and more exposed to space radiation.

Satellite Operations

Highly energetic ions penetrate electronic components, causing bit-flips in a chain of electronic signals that can result in improper commands within the spacecraft or incorrect data from an instrument. Less energetic particles contribute to a variety of spacecraft surface charging problems, especially during periods of high geomagnetic activity.

Surveying

Magnetic field changes associated with geomagnetic storms directly affect operations that use the Earth’s magnetic field for guidance, such as magnetic surveys, directional drilling, or the use of magnetic compasses. Ionospheric disturbances cause errors in location obtained from GPS signals.

Communications

Communications at all frequencies may be affected by space weather. High frequency (HF) radio communications are more routinely affected because this frequency band depends on reflection by the ionosphere to carry signals great distances.

Video: An Introduction to Space Weather and the Space Weather Prediction Center (4:57 min)

This video summarizes the impacts of space weather, and what the National Weather Service is doing to protect us.