A geomagnetic storm is set to hit Earth on Saturday after the Sun blasted out millions of tons of ionised gas from one of five sun-spot clusters late on Thursday and may affect GPS signals, satellites and the electricity grid. The solar storm could also touch off geomagnetic activity that could make the Northern Lights visible as far south as the Hudson Valley New York.

The Solar Dynamics Observatory of the National Aeronautics and Space Administration (Nasa) captured a “significant solar flare” erupting from the Sun. The US space agency said on Friday that the Sun on Thursday emitted an X1-class flare. “POW! The sun just served up a powerful flare,” Nasa tweeted.

Nasa says 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, etc.

When the solar flare— powerful bursts of radiation—erupted on Thursday, it caused a strong radio blackout storm, which can disrupt some high-frequency radio broadcasts and low-frequency navigation.

Spaceweather.com reported that the flare originated from a sunspot called AR2887 currently positioned in the centre of the Sun and facing the Earth, based on its location.

The US Space Weather Prediction Center (SWPC) said the X1-class flare caused a temporary, yet strong radio blackout across the sunlit side of Earth-centered on South America.

William Murtagh, SWPC director, said that of the five sunspot clusters, those large magnetic storms that appear darker than the rest of the sun, only two are likely to cause the Earth any trouble. According to Nasa, the X1-flare is also likely to hit Earth’s magnetic field on Saturday.

The harmful radiation from a solar flare cannot pass through Earth’s atmosphere to affect humans but they can disturb the atmosphere in the layer where GPS and communications signals travel.

When these intense flares are aimed directly at Earth, they can also be accompanied by a massive eruption of solar particles, called a coronal mass ejection. The SWPC said that the impulsive X1-class flare on Thursday also “appeared to have coronal mass ejection related signatures”.

The wave of solar energy may also deliver a celestial show for sky-watchers in the Northern Hemisphere when it hits. However, for observers along the Eastern Seaboard the potential for weekend rain may dampen viewing opportunities.

When a wave of solar energy hits Earth’s magnetic field it will often create an aurora at the poles—in the Northern Hemisphere this is often called the Northern Lights and can appear as colourful ribbons in the sky or just flickering.

“We think the initial impact will happen during the daylight hours, so for aurora enthusiasts in the US, we are looking at overnight of the 30th into 31st for the best chance to see the aurora,” Murtagh was quoted as saying by Bloomberg.

The solar storm is rated as G3 on the five-step scale for ranking such events, lower than the level where power grid operators become concerned.