Solar flare
Other large solar flares also occurred on April 2, 2001 (X20), October 28, 2003 (X17.2 and 10), September 7, 2005 (X17), February 17, 2011 (X2), August 9, 2011 (X6.9), March 7, 2012 (X5.4), July 6, 2012 (X1.1). On July 6, 2012, a solar storm hit just after midnight UK time, when an X1.1 solar flare fired out of the AR1515 sunspot. Another X1.4 solar flare from AR 1520 region of the Sun, second in the week, reached the Earth on July 15, 2012 with a geomagnetic storm of G1–G2 level. A X1.8-class flare was recorded on October 24, 2012. There has been major solar flare activity in early 2013, notably within a 48-hour period starting on May 12, 2013, a total of four X-class solar flares were emitted ranging from an X1.2 and upwards of an X3.2, the latter of which was one of the largest year 2013 flares. Departing sunspot complex AR2035-AR2046 erupted on April 25, 2014 at 0032 UT, producing a strong X1.3-class solar flare and an HF communications blackout on the day-side of Earth. NASA's Solar Dynamics Observatory recorded a flash of extreme ultraviolet radiation from the explosion. The Solar Dynamics Observatory recorded an X9.3-class flare at around 1200 UTC on September 6, 2017.
Human spaceflight
Without proper shielding, the crews of missions beyond low Earth orbit (LEO) might be at risk from high-energy protons emitted by solar flares and associated solar particle events (SPEs). Lawrence Townsend of the University of Tennessee and others have studied the overall most powerful solar storm ever recorded. The flare was seen by the British astronomer Richard Carrington in September 1859. Radiation doses astronauts would receive from a Carrington-type storm could cause acute radiation sickness and possibly even death. Another storm that could have incurred a lethal radiation dose if astronauts were outside the Earth's protective magnetosphere occurred during the Space Age, in fact, shortly after Apollo 16 landed and before Apollo 17 launched. This solar storm of August 1972 would likely at least have caused acute illness.