The Early History of Space Weather: Observations that Connected Solar Activity and its Influence on the Earth

Storms on Earth, such as hurricanes, can have devastating consequences for our planet's inhabitants. But a potentially more catastrophic “storm” can come from our own Sun. As early as 1722 compass maker George Graham realized mysterious movement he saw in his compass needles correlated to the appearance of aurora, suggesting the phenomena were related. In 1859, the largest solar flare (the Carrington event) preceded intense auroral activity worldwide for many days and caused disturbances in the nascent telegraphic industry. And in the late 1870s William Ellis offered the first known forecast of severe electrical currents on Earth due to solar activity in 1879, when he warned that sensitive telegraphic equipment might react to an upcoming increase in solar activity. This talk will focus on these early observers and how their discoveries led to the "space weather" that can influence the performance of space-borne and ground-based technological systems and endanger human life or health.