What Is Space Weather and How Does It Affect the Earth?
Space weather is very different from weather on Earth. Weather on Earth involves atmospheric conditions, such as temperature, humidity, and air pressure, that can produce storms with precipitation and wind. In the vacuum of space, there is no water or air, and thus there also isn’t any precipitation. But there is wind — solar wind — that isn’t air at all, but instead is a stream of energy and plasma, or charged particles, from the Sun. Space weather storms are invisible but still impact Earth.
What Are Space Weather Storms?
Space weather begins with the Sun. The Sun gives off electromagnetic energy in many wavelengths, including visible light, radio waves, ultraviolet, high energy X-rays, and more. The Sun also emits a stream of radiation in the form of charged particles (plasma) that make up the solar wind. Occasional energy bursts resulting from huge explosions on the Sun send plasma and radiation hurtling through our solar system, sometimes in the direction of Earth. Solar flares, coronal mass ejections (CMEs), and solar prominence events are examples of solar phenomena that can release these energy bursts toward Earth and create space weather storms.
NASA Goddard Space Flight Center
Space Weather Interacts With Earth’s Atmosphere
As the solar wind flows past Earth, it mostly deflects around Earth's magnetosphere, the protective magnetic field that surrounds our fragile planet. Bursts of solar energy that travel toward Earth smash into the magnetosphere, sending particle radiation spiraling down along our planet's magnetic field lines. As these radiation particles collide with atoms in Earth's upper atmosphere, the resulting space weather storms sometimes produce the spectacular light shows called auroras — the northern and southern lights. Space weather can also interfere with satellite electronics, radio communications, GPS signals, spacecraft orbits, and even electrical power grids on Earth.
Coronal mass ejections (CMEs) create space weather events that interact with Earth’s magnetosphere to create auroras, as seen from space (middle) and from Earth (right).
SOHO/NASA
Solar Flares Can Cause Radio Blackouts
Solar flares emit X-rays, among other types of electromagnetic energy. Increased X-ray emissions can scatter radio waves as a result of disruptions to the ionosphere, causing radio blackouts on Earth. Radio blackouts can last for a few minutes or even several hours and are the most common type of space weather impact experienced on Earth. There are on average 2000 radio blackouts due to solar activity during each 11-year solar cycle. The energy from solar flares reaches Earth in about eight minutes, which doesn’t leave much time for advance notice. Because of this, scientists continually monitor the Sun to make sure they can get alerts out as quickly as possible.
Solar Radiation Storms
Solar radiation storms are caused by both solar flares and coronal mass ejections. During a solar radiation storm, large bursts of protons and other particles from the Sun can increase the amount of radiation near Earth to harmful levels that can have dangerous health effects for astronauts at the International Space Station and, in some cases, even for airline travelers in polar regions. This increased energy can also cause severe damage to satellite electronics and can interact with Earth’s ionosphere to temporarily disrupt radio communication in polar areas. Radiation storms reach Earth within 10 minutes of a solar event and can impact the planet for time periods of hours to days.
Geomagnetic Storms
A coronal mass ejection sends a burst of solar particles and radiation toward Earth. Much of the energy is deflected around Earth due to our magnetosphere, but some interacts with our atmosphere causing geomagnetic and solar radiation storms.
COMET
A large coronal mass ejection can cause a strong gust of solar wind to reach Earth, transferring energy to Earth’s magnetic field and causing a geomagnetic storm. These storms can create intense currents in Earth’s magnetosphere and cause the ionosphere and upper thermosphere to heat up. The most common effect on Earth is spectacular auroras, but they can also disrupt radio signals and navigation systems, create drag for low-orbiting satellites, and harm power grids. Geomagnetic storms typically take several days to reach the Earth so warnings can be issued well before they arrive. Effects of geomagnetic storms can last for several days.