1859

Solar Flares and Space Weather

Richard Carrington (1826–1875)

The Sun is the most massive, energetic, and important (to us, at least) non-Earth object in the solar system, and so it should not be surprising that many astronomers have chosen to train their increasingly powerful telescopes on our nearby star in order to study its inner workings. By using proper filters or projecting the solar disk onto a wall or screen, astronomers could measure and monitor features like sunspots on the Sun’s visible “surface,” the photosphere. Sunspots had been studied for centuries, with telescopic observations going back to the early seventeenth century, and naked-eye (filtered) observations spanning an even longer history. Improvements in telescopes and observing methods over time have allowed sunspots to be studied in ever more exquisite detail.

One of the most noted and prolific observers of sunspots was the English amateur astronomer Richard Carrington. On September 1, 1859, Carrington observed an intense brightening on the Sun near a particularly dense cluster of sunspots. The event lasted only a few minutes. The next day, however, saw reports from around the world of intense auroral activity and major disruptions to telegraphs and other electrical systems.

What Carrington had witnessed was the first recorded example of a solar flare—
an enormous explosion in the Sun’s atmosphere that can hurl high-energy particles at enormous speeds out into the solar system. The dramatic effects from this solar “wind” crashing into the Earth’s protective magnetic field are known as a solar storm. Many such flares and storms have been observed since then, but visual records and ice-core data indicate that the 1859 event was not only the first but also the largest in recorded history—perhaps a once-in-a-millennium mega-flare.

Carrington’s scientific observations established a connection between the Sun’s activity and the Earth’s environment and led to intense interest in the study of space weather—the interaction of the solar wind with all the planets. Today’s armada of Earth-orbiting communications, weather, and remote-sensing satellites, in particular, represents billions of dollars of technology and infrastructure that is highly vulnerable to disruption by solar flares and their ensuing storms. This is just one reason why NASA and other space agencies are highly motivated to continue Carrington’s important work of predicting, monitoring, and understanding the effects of space weather.

SEE ALSO Airborne Remote Sensing (1858), Reversing Magnetic Polarity (1963), Magnetic Navigation (1975), The Oscillating Magnetosphere (1984)

A spectacular solar-prominence eruption captured in time-lapse frames on March 30, 2010, in the extreme ultraviolet light of ionized helium by the NASA Solar Dynamics Observatory satellite. For scale, hundreds of Earths would fit into the loop in the top frame.