Nasa says biggest solar flare in three years could be sun 'waking up'

US space agency Nasa has said the sun's solar cycle could be "waking up" after the biggest solar flare recorded in almost three years.

Nasa spacecraft spotted the new family of sunspots appearing on the face of the sun.

The dark spots are really magnetic fields created by the sun's gas, and these magnetic fields go through a cycle roughly 11 years in length.

The solar flares can be detected in the top left corner of this image. Photo / Nasa, Solar Dynamics Observatory

At the end of this cycle, the sun's magnetic fields flip and the cycle starts all over again.

Eruptions increase during the cycle with solar flares like the recent one detected by Nasa, as well as "coronal mass ejections", where the sun shoots out plasma, becoming more frequent.

Sun spots increase until the middle of the cycle, known as the solar maximum, before decreasing in time as the cycle returns to the solar minimum.

Nasa has said the recent detection shows we could be moving out of the solar minimum.

While some people worry about a "killer solar flare" unleashing so much energy it wipes out Earth, according to Nasa that isn't actually possible.

But the eruptions which occur throughout the cycle can have an effect on Earth if they're powerful enough.

They can cause breathtaking auroras in the night sky or take down GPS and radio communications by disrupting their signal transmissions.

According to Nasa, if there was a strong enough eruption it could even impact on our electricity grids.

The most recent solar flare, which was detected last Friday morning, wasn't powerful enough to do that, or even powerful enough to prompt Nasa to send an alert about it, but in an announcement the next day the agency said it could be the first signs that the sun's solar cycle is ramping up.

"The intensity of this flare was below the threshold that could affect geomagnetic space and below the threshold to create an alert," the agency said.

"Nonetheless, it was the first M-class flare since October 2017 – and scientists will be watching to see if the sun is indeed beginning to wake up."

Nasa said it will be a few months before we know for sure.

The solar minimum is when the sun has the lowest number of sunspots throughout its whole cycle, so the amount of spots needs to consistently rise before the minimum can be identified.

"This is partly because our star is extremely variable," Nasa said.

"Just because the sunspot numbers go up or down in a given month doesn't mean it won't reverse course the next month, only to go back again the month after that. So, scientists need long-term data to build a picture of the sun's overall trends through the solar cycle."