A coronal mass ejection (CME) is a significant release of plasma and accompanying magnetic field from the corona of the sun. CME's often follow solar flares and are normally present during a solar prominence eruption. Do they hit earth? Sure – one most recently in 1859. What would happen if a CME strikes again?
The solar storm of 1859 (also known as the Carrington Event) was a powerful geomagnetic storm during Solar Cycle 10 (1855–1867). A solar coronal mass ejection hit Earth's magnetosphere and induced the largest geomagnetic storm ever recorded on September 1–2, 1859. The storm caused strong auroral displays and wrought havoc with telegraph systems, essentially frying all the lines. A solar storm of this magnitude occurring today would cause unimaginably widespread electrical disruptions, blackouts and damage due to extended outages of the electrical grid.
A solar storm in 2012 was of similar magnitude, but it passed Earth's orbit without striking the planet, missing us by nine days. If the huge solar eruption in 2012 had hit the Earth, the effects would have been so devastating that those of us remaining would still be recovering from it. A huge CME or cloud of hot plasma erupted from the sun on July 23, 2012. The CME did go through Earth's orbit, and had it happened only nine days earlier, our planet would have been in the way and faced severe technological consequences.
There would have been three waves of damage associated with the extreme solar storm. First, X-rays and ultraviolet radiation from the solar flare would have produced radio blackouts and GPS navigational errors. The second part would have seen satellites fried by energetic particles like electrons and protons, arriving only minutes to hours later. Finally, magnetized plasma from the CME would have struck our planet within the next day. Power blackouts would have been devastating, wiping out the power grid, making it difficult to even flush the toilet because most urban areas use electric water pumps. Earth and its inhabitants were incredibly fortunate that the 2012 eruption happened when it did.
Experts generally expect a bad solar storm to reach Earth about once every century. Scientists drilling at the poles and taking ice core samples see the evidence of large solar flares hitting the Earth every 100-150 years. It seems we are overdue. A solar storm of the same magnitude as 1859 and 2012 occurring today would cause widespread electrical disruptions, blackouts and damage due to extended outages of the electrical grid.
Solar Cycle 25 should begin between mid-2019 and late 2020 and should reach its maximum between 2023 and 2026, when between 95 and 130 sunspots are projected. What are the chances that we experience a CME in the next decade? Probably good. It is all a roll of the dice, but there is an absolute 100 percent certainty it will happen at some time in the future.
How many people could die due to a large flare? When scientists are asked, their response is that should a large electromagnetic pulse (EMP) or geomagnetic disturbance (GMD) event occur due to a CME, as many as 9 out of 10 people in the United States could die. Civilization as we know it would essentially end along with our technological capabilities. But who knows? So, on that cheery note, open another bottle and pour me a glass, and would you pass the pretzels please?