Space weather

Lore & Background

For centuries, the effects of space weather were noticed but not understood, such as auroral displays at high latitudes. In 1724, George Graham reported that a magnetic compass needle was regularly deflected from magnetic north over each day, a phenomenon later attributed to overhead electric currents in the ionosphere and magnetosphere by Balfour Stewart in 1882 and confirmed by Arthur Schuster in 1889. In 1852, Edward Sabine showed that geomagnetic storm occurrence correlated with sunspot numbers, demonstrating a novel solar-terrestrial interaction. The solar storm of 1859 caused brilliant aurorae and disrupted global telegraph operations; Richard Carrington connected it to a solar flare observed the day before. Kristian Birkeland explained auroral physics by creating artificial aurorae in his laboratory and predicted the solar wind. The introduction of radio revealed that solar weather could cause extreme static or noise, and radar jamming during a large solar event in 1942 led to the discovery of solar radio bursts.

In the 20th century, interest expanded as military and commercial systems became dependent on technologies affected by space weather. The International Geophysical Year increased research; ground-based data showed aurorae occur in an auroral oval. In 1958, Explorer I discovered the Van Allen belts, and in January 1959, Luna 1 first directly observed the solar wind. In 1969, INJUN-5 made the first direct observation of the electric field impressed on Earth's high-latitude ionosphere by the solar wind. In the early 1970s, Triad data demonstrated permanent electric currents between the auroral oval and magnetosphere. The term 'space weather' came into usage in the late 1950s and regained popularity in the 1990s.

Reader's Guide

Space weather's significance lies in its direct impact on modern technological systems. Communications satellites, weather satellites, and GPS signals can be interfered with or damaged by space weather phenomena, which also cause damaging surges in long-distance transmission lines and expose aircraft passengers and crew to radiation, especially on polar routes. The US National Space Weather Program was established to focus research on the needs of commercial and military communities, connect research and user communities, and coordinate operational data centers. In late 2019, the International Civil Aviation Organization implemented a Space Weather Advisory program, designating four global service providers: the United States (NOAA Space Weather Prediction Center), the ACFJ consortium (Australia, Canada, France, Japan), the PECASUS consortium (Finland, Belgium, UK, Poland, Germany, Netherlands, Italy, Austria, Cyprus), and the China-Russian Federation Consortium. Space weather is listed as a natural hazard in risk assessments of Ireland, the United Kingdom, and New Zealand. Phenomena include geomagnetic storms, energization of Van Allen belts, ionospheric disturbances, scintillation of satellite-to-ground signals, aurorae, and geomagnetically induced currents. Coronal mass ejections can compress the magnetosphere and trigger storms, while solar energetic particles can damage spacecraft electronics and threaten astronauts. Spacecraft failures are often attributed to space weather; 46 of 70 failures in 2003 occurred during the October 2003 geomagnetic storm. Common effects are radiation damage (causing single event upsets or latchups) and spacecraft charging from low-energy particles, which can cause discharges. Geomagnetic storms also heat the thermosphere, increasing drag on low Earth orbit spacecraft and accelerating orbital decay.

Did You Know?

• The term 'space weather' was first used in the 1950s and popularized in the 1990s.
• The solar storm of 1859 disrupted global telegraph operations and caused brilliant auroral displays.
• In January 1959, the Soviet satellite Luna 1 first directly observed the solar wind.