A stream of highly charged particles from the sun is headed straight toward Earth, threatening to plunge（颠覆） cities around the world into darkness and bring the global economy（经济） screeching（尖锐） to a halt.

This isn't the premise（前提） of the latest doomsday（世界末日） thriller（感兴趣的事）. Massive solar storms have happened before — and another one is likely to occur soon, according to Mike Hapgood, a space weather scientist at the Rutherford Appleton Laboratory（实验室） near Oxford, England.

Much of the planet's electronic equipment, as well as orbiting（轨道） satellites, have been built to withstand these periodic（周期性） geomagnetic（地磁） storms. But the world is still not prepared for a truly damaging solar storm, Hapgood argues in a recent commentary（评论） published in the journal Nature.

Hapgood talked with The Times about the potential effects of such a storm and how the world should prepare for it.

What exactly is a solar storm?

I find that's hard to answer. The term "solar storm" has crept into our usage（用法）, but nobody has defined what it means. Whether a "solar storm" is happening on the sun or is referring to the effect on the Earth depends on who's talking.

I prefer "space weather," because it focuses our attention on the phenomena（现象） in space that travel from the sun to the Earth.

People often talk about solar flares（喇叭裤） and solar storms in the same breath. What's the difference?

Solar flares mainly emit（喷出） X-rays — we also get radio waves from these things, and white light in the brightest of flares. They all travel at the same speed as light, so it takes eight minutes to arrive. There are some effects from flares, such as radio interference from the radio bursts（突然打开）.

But that's a pretty相当 small-beer微不足道 thing. The big thing is the geomagnetic storms [on Earth] that affect the power grid坐标网格, and that's caused by the coronal花冠头部 mass ejections [from the sun].

Coronal mass ejections喷出 are caused when the magnetic磁性 field in the sun's atmosphere gets disrupted扰乱 and then the plasma等离子体, the sun's hot ionized使电离的 gas, erupts爆炸 and send charged particles into space. Think of it like a hurricane 飓风— is it headed toward us or not headed toward us? If we're lucky, it misses us.

How are solar flares and coronal mass ejections related?

There's an association between flares and coronal mass ejections, but it's a relationship we don't quite understand scientifically. Sometimes the CME launches发生 before the flare occurs, and vice versa.

What happens when those particles reach Earth?

There can be a whole range of effects. The classic one everyone quotes is the effect on the power grid. A big geomagnetic storm can essentially put extra electric currents into the grid. If it gets bad enough, you can have a complete failure of the power grid — it happened in Quebec back in 1989. If you've got that, then you've just got to get it back on again. But you could also damage the transformers变压器, which would make it much harder to get the electric power back.

How else could people be affected?

You get big disturbances in the Earth's upper atmosphere — what we call the ionosphere电离层 — and that could be very disruptive分裂 to things like GPS [the network of global positioning system satellites]. Given the extent we use GPS in everyday life [including for cellphone无线电话 networks, shipping safety and financial transaction records], that's a big issue.

The storms can also disrupt communications on transoceanic 跨洋flights. Sometimes when that happens, they will either divert or cancel flights. So that would be the like the disruption we had in Europe from the volcano two years ago, where they had to close down airspace for safety reasons.

What went wrong in the 1989 storm?

In the U.K., there were two damaged transformers that had to be repaired. But no power cuts. The worst thing is what happened in Quebec. In Quebec, the power system went from normal operation to failure in 90 seconds. It  affected around 6 million people. The impact was reckoned估计 to be $2 billion Canadian in 1989 prices.

We had lots of disruption to communications to spacecraft operations. The North American Aerospace Defense Command has big radars tracking跟踪 everything in space, and as they describe it, they lost 1,600 space objects. They found them again, but for a few days they didn't know where they were.