New research from the University of St Andrews has proposed that particles in solar flares are 6.5 times hotter than previously thought. The research provides an unexpected solution to a 50-year-old mystery about our nearest star.

Solar flares are sudden and huge releases of energy in the sun's outer atmosphere that heat parts of it to greater than 10 million degrees. These dramatic events greatly increase the solar X-rays and radiation reaching Earth and are hazardous to spacecraft and astronauts, as well as affecting our planet's upper atmosphere.

The research, published in The Astrophysical Journal Letters, looks at evidence of how flares heat solar plasma to greater than 10 million degrees. This solar plasma is made up of ions and electrons. The new research argues that solar flare ions, positively charged particles that make up half of the plasma, can reach over 60 million degrees.