VOA慢速英语：太阳活动影响地球上通讯和能源活动

Scientists who study the sun watch for sunspots -- violent storms that canaffect communications, navigation systems and even electric power stationson Earth.

One of those scientists is Alex Young of the Goddard Space Flight Center inGreenbelt, Maryland. Crews at Goddard are studying the Earth and our solarsystem for NASA, the National Aeronautics and Space Administration. Mr.Young recently told VOA what the space agency is learning about the sun.

Sunspots are a product of huge electromagnetic storms on the sun.Scientists on Earth are able to observe sunspots eight minutes after theyhappen. That is how long it takes for the sun’s light to reach us.

"Sunspots" are actually violent storms. Space scientists closely observe this activity because it may affect communications, navigation and even power grids on earth.

The first electrically charged particles from a sunspot enter Earth’satmosphere about 20 to 30 minutes after the storm happens. These particlescan harm human beings. So before they arrive, astronauts on the InternationalSpace Station move into special areas designed to protect them from theireffects.

About a day or two later, the biggest part of the storm arrives. It is called acoronal mass ejection.

“That is billions of tons of solar material that’s blown away from the sun. (When) it’s traveling millions of kilometers an hour, but that is relatively slow.”

That is Alex Young. He is the Associate Director for Science at NASA’sHeliophysics Science Division.

Several civilian government agencies and the U.S. Air Force watch weatherconditions in space 24 hours a day. NASA does so because it must protect itsastronauts and the electronic devices on its spacecraft.

Scientists are also trying to understand why the number of sunspots rises andfalls at almost regular intervals every 11 years. In other words, scientists canalmost predict the amount of solar activity.

“Also, sometimes the intensity is higher, sometimes lower. For example, thecurrent solar cycle, as we call it, that we are in, is much lower than theprevious one.”

Several satellites watch the sun and the environment between the sun and theearth. Pictures and other information from the satellites tell scientists what ishappening on and near the sun.

Alex Young says we have only been looking at the sun with powerfulinstruments for about 30 to 40 years. That is a very short time compared to the four billion years that the star has been shining.

I’m Jim Tedder.

VOA’s George Putic reported this story from Washington. Christopher Jones-Cruise adapted it for Learning English. George Grow was the editor.

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Words in This Story

navigation – n. the act, activity or process of finding the way to get to a placewhen traveling

electromagnetic– adj. relating to electromagnetism, the study of a kind ofphysical interaction that takes place between electrically charged particles

relatively – adv. when compared to others

cycle– n. a series of events or actions that happen again and again in thesame order; a repeating series of events or actions