Article Posted on : - Nov 01, 2013

A file photo.

WASHINGTON (PTI): The Sun has emitted a large solar flare - its fourth X-class flare in the last week, NASA said.

The flare is its fourth X-class flare since October 23, 2013 - peaking on October 29.

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 the 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.

This flare is classified as an X2.3 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 and so on, said NASA.

Increased numbers of flares are quite common at the moment, since the Sun's normal 11-year activity cycle is ramping up towards solar maximum conditions.

Humans have tracked this solar cycle continuously since it was discovered in 1843, and it is normal for there to be many flares a day during the Sun's peak activity.