The biggest solar flare in four years erupted from the sun on Tuesday and is heading towards Earth in an event that could disrupt power grids and satellites.

The flare's climax was on Tuesday, creating a massive cloud that covered almost half the sun, NASA said.

A solar flare is a sudden brightening observed over the sun's surface or the solar limb, which is interpreted as a large energy release of up to 6 × 1025 joules of energy. (about a sixth of the total energy output of the Sun each second). The term is also used to refer to similar phenomena in other stars, where the term stellar flare applies.

Below is an amazing photo of the solar flare from Tuesday and photos from various solar activities on other dates.

Coronal Mass Ejection as viewed by the Solar Dynamics Observatory on June 7, 2011.
A solar flare erupted on Tuesday in the Sun is heading towards the Earth that could disrupt power grids and satellites. The solar flare, which is backed by a small radiation storm and a spectacular coronal mass ejection (CME), might stimulate auroras on Thursday. NASA/SDO
Solar flare image from NASA
Solar flare image from NASA REUTERS
SOLAR ACTIVITY IS SEEN IN AN IMAGE FROM NASA AFTER DISCHARGE OF HUGE CLOUD OF CHARGE PARTICLES.
Solar activity is shown in an image made by NASA's SOHO Large Angle and Spectrometric Coronagraph (LASCO) instrument at 6:30 a.m. (1130 GMT) on October 28, 2003. The cloud, known to astronomers as a coronal mass ejection, is the one of the strongest ever detected since scientists started measuring these phenomena a quarter-century ago. When that cloud of particles gets here, perhaps by midday Wednesday, it could have severe effects, such as affecting some modern electronics and navigation equipment. Reuters
SOLAR ACTIVITY IS SEEN IN AN IMAGE FROM NASA AFTER DISCHARGE OF HUGE CLOUD OF CHARGE PARTICLES.
Solar activity is shown in an image made by NASA's SOHO Large Angle and Spectrometric Coronagraph (LASCO) instrument at 6:30 a.m. (1130 GMT) on October 28, 2003. The cloud, known to astronomers as a coronal mass ejection, is the one of the strongest ever detected since scientists started measuring these phenomena a quarter-century ago. When that cloud of particles gets here, perhaps by midday Wednesday, it could have severe effects, such as affecting some modern electronics and navigation equipment. Reuters
NASA image of the Sun showing nearly simultaneous solar eruptions
This image of the sun, captured by The Solar Dynamics Observatory spacecraft January 28, 2011, shows nearly simultaneous solar eruptions on opposite sides of the Sun, in this photograph released by NASA January 28. A filament on the left side became unstable and erupted, while an M-1 flare and a coronal mass ejection on the right blasted into space. Reuters
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