The sun was rocked by an extremely powerful solar flare on Tuesday, which, according to scientists, was the largest in four years. However, the bursts of radiation were not likely to cause any serious chaos on Earth since they were not aimed at the planet, they added.

The solar flare, which began at around 3:48 a.m. EDT, was measured under an X6.9 scale. Scientists measure the strength of solar flares under three class scales - class X, class C and class M. Among these three, class X is the strongest type of eruption, while class C refers to the weakest and class M represents medium-strength eruptions.

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This still from a video taken by NASA's Solar Dynamics Observatory shows the Aug. 8, 2011 solar flare as it appeared in the ultraviolet range of the light spectrum. The flare registered as an X6.9 class sun storm, the largest of the Solar Cycle 24. Photo: NASA/SDO/GSFC

"It was a big flare," said Joe Kunches, a space scientist with the National Oceanic and Atmospheric Administration (NOAA)'s Space Weather Prediction Center. "We lucked out because the site of the eruption at the sun was not facing the Earth, so we will probably feel no ill effects."

Largest flare yet

Scientists said that Tuesday's flare was the largest one so far in the sun's current cycle. They also said that the current cycle, which began in 2008, is likely to last until around 2020.

"This flare had a GOES X-ray magnitude of X6.9, meaning it was more than three times larger than the previous largest flare of this solar cycle - the X2.2 that occurred on Feb 15, 2011," scientists with NASA's Solar Dynamics Observatory, a space observatory that monitors the sun, wrote in an update.

The Feb. 15 storm followed another massive solar flare occurred in December 2006, which was rated as an X9-class solar storm.

Solar flares occurred as a result of sun's magnetic field lines tangling up into knots. The knots build potential energy until they end up with a tipping point. After that the energy is converted into heat, light and the motion of charged particles, according to a Space.com report.

When do they pose threat to Earth?

Even if all the X class solar storms are major events, they don't pose any threat to Earth until they are aimed directly at the blue planet.

According to NASA, the massive bursts of radiation cannot pass through Earth's atmosphere to harm humans on the ground, but they can disrupt the atmosphere and disrupt GPS and communications signals. In this case, the flare packed a punch strong enough to potentially cause some radio communication blackouts.

Scientists said that during eruptions, sun releases a cloud of plasma called a coronal mass ejection into space, and sometimes toward Earth.

Although Tuesday's solar flare and resulting coronal mass ejection (CME) was not aimed at Earth, some VLF and HF radio communications blackouts have been reported, Spaceweather.com said.

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