The largest solar storm in five years hit our planet early Thursday, but didn't deliver as much punch as some space weather specialists had predicted.

There was some concern among scientists that the storm would impact power grids, airplane routes and space-based satellite navigators.

But according to preliminary analysis from NASA, humankind's maze of power plants and navigation systems weathered the storm well.

"It looks to me like it's over," said NASA solar physicist David Hathaway Thursday afternoon, adding a key magnetic reading had dropped.

Still, some experts are warning that the solar storm could continue and even intensify into Friday.

Doug Biesecker, a scientist at the National Oceanic and Atmospheric Administration's Space Weather Prediction Center, said that a different magnetic field measurement system painted a different picture.

The storm started with a pair of massive solar flares that were ejected from the sun's atmosphere earlier in the week. That sent a massive cloud of charged particles hurtling through space for almost two days, growing like a giant bubble as it travelled.

The particles were moving at roughly 6.4 million kilometres per hour when the cloud reached Earth around 5:45 a.m. ET Thursday.

Rob Steenburgh, a forecaster at the Space Weather Prediction Center, said shortly before 5 a.m. ET, there still had been no noticeable effects on Earth or on a satellite geared to monitor the storm's impact.

And when the storm arrived, the power stayed on and GPS satellites kept working – a result one scientist attributed to luck.

"I think we just lucked out," said Boston University's Jeffrey Hughes, director of the Center for Integrated Space Weather Modeling.

"It just didn't pack as strong a magnetic field as we were anticipating."

The first bit of solar radiation hit Earth's magnetic field on Wednesday. The effects of this phase on satellites and air traffic near the North and South Poles are expected to last for days.

The plasma cloud that hit early Thursday was expected to disrupt high-accuracy GPS systems used by surveyors, while sparing the GPS devices often used in vehicles.

But since this storm had a northern orientation when it hit Earth, the impact was less severe. Scientists said that storms orientated toward the south are more damaging and have cause bigger auroras.

Astronomers say this storm is part of the sun's normal 11-year magnetic activity cycle. That cycle is expected to reach its peak next year, scientists say, when the sun will emit several storms a day, rather than just once a week as it normally does.

While solar storms don't harm people, scientists are only beginning to realize how much they can disrupt our technology. The last time the sun's activity cycle reached its peak was 10 years ago, when experts learned how vulnerable GPS can be to solar outbursts.

New satellite technology has flourished in the decade since then, so scientists are hoping to use the cycle peak to learn more the vulnerabilities of technology.

In Quebec, 6 million people lost power when a solar storm hit in 1989.

With reports from Angela Mulholland and The Associated Press