On September 1, 1859 Richard Carrington observed a solar flare while drawing sunspots. Rather than look at the same drawing of sunspots that we always see, let's look at the magnetometer records released this year by the British Geological Survey (see "Search the Collection" at this link.) Magnetometers measure the strength and direction of the Earth's magnetic field. BGS scanned and released the records from several stations, including the Greenwich station we show here.
On the top is the day of the flare. In the oval in the upper right is the effect of the solar flare at 11:18 am. (Perhaps you can figure out the times in these plots!) Other than a few small changes, the traces on 9/1/1859 look pretty smooth.
A coronal mass ejection, a large surge of particles from the Sun, often comes with a flare. In the lower plot are the traces from two days later, while the particles ejected from the Sun at the same time as the 9/1/1859 flare are hitting the Earth's magnetosphere. The traces cover the page, with many rapid changes. People started associating flares on the Sun with the changes in the magnetic field being measured by the magnetometers.
This was not just scientific curiosity. Those changes in the magnetic field affected the telegraph system, shocking the operators and allowing them to send messages without batteries while the aurora caused by the solar storm pulsed overhead.
Today we watch the Sun for signs of flares and coronal mass ejections with SDO and other satellites. We monitor the Earth's magnetic field at stations of the BGS and other organizations. Space weather continues to affect our lives when it disrupts radio communications just like it disrupted telegraphs in early September, 1859.
This anniversary was celebrated on The Writer's Almanac, along with a poem about watching a James Bond movie.
Happy Birthday, Space Weather!
