This is the first significant flare of 2014, and follows on the heels of mid-level flare earlier in the day.
Each flare was centred over a different area of a large sunspot group currently situated at the centre of the Sun, about half way through its 14-day journey across the front of the disk along with the rotation of the Sun.
One of the largest sunspots in the last nine years, named AR1944, was seen, as captured by NASA's Solar Dynamics Observatory.
Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground.
However, when intense enough, they can disturb the atmosphere in the layer where Global Positioning System (GPS) and communications signals travel.
This disrupts the radio signals for as long as the flare is ongoing, anywhere from minutes to hours, the US space agency said.
This flare is classified as an X1.2-class flare. X-class denotes the most intense flares, while the number provides more information about its strength.
An X2 is twice as intense as an X1, an X3 is three times as intense.