NASA发现了有关太阳风的新细节

Scientists say a spacecraft flying very close to the sun has uncovered new details about the nature of solar wind.

Solar wind is created by a continuous flow of charged particles, known as plasma, that are released into space from the sun's outermost atmosphere. That atmosphere is known as the corona.

Researchers recently announced they had learned new information about solar wind from data collected by the Parker Solar Probe. The American space agency NASA operates the spacecraft.

NASA launched the Parker Solar Probe in 2018 with a main goal of studying solar wind. Scientists say studying solar wind and the corona close up is important to learn how solar activity influences Earth.

Unlike Earth, the sun does not have a solid surface. Instead, it is a superheated ball of material held together by gravity and magnetic forces. Some solar material escapes from the sun and is released into space as solar wind.

In 2021, researchers announced that the Parker Solar Probe had entered the sun's corona for the very first time. NASA described the successful operation as "touching" the sun. Scientists said Parker was about 13 million kilometers from the center of the sun when it crossed into the sun's outer atmosphere.

Data collected by the spacecraft showed that solar wind can reach speeds up to 1.6 million kilometers per hour. Solar wind forms a large magnetic barrier known as the heliosphere. It protects Earth and other planets from the continuous flow of high-energy particles from the sun's corona.

The researchers recently reported their findings in a study published in Nature.

The team said the collected data suggests these particles get blasted from the sun in a similar way that water shoots out from a shower head. The particles are released through holes in the sun's corona. The researchers said the data suggests these openings are the source of solar wind.

Past research had found that the sun's magnetic field was somehow driving solar wind. This study is the first to identify its source.

James Drake is a professor of physics at the University of Maryland and a lead writer of the study. He said in a statement, "Winds carry lots of information from the sun to Earth, so understanding the (source) behind the sun's wind is important for practical reasons on Earth."

Drake said that understanding how the sun releases energy can help scientists learn how to prepare for solar storms that can affect Earth. For example, intense solar activity can cause solar flares, explosions of electromagnetic radiation from the sun. This can interfere with different radio communication signals on Earth.

The researchers said the data showed that the holes in the sun's corona are usually in areas around the poles during the sun's quiet periods. This prevents the speeding particles from affecting Earth.

However, the team noted that the sun becomes active every 11 years as its magnetic field changes and the poles exchange positions. This results in "bursts of solar wind aimed directly at Earth," the researchers said in a statement.

The researchers used data from the Parker Solar Probe to examine plasma flowing out of the corona. Data for the latest research was collected at a distance of about 9 million kilometers from the sun, the team said.

"When you get very close to the sun, you start seeing stuff that you just can't see from Earth," Drake said. He added that the findings were only possible because the Parker Solar Probe was able to pass so close to the surface of the sun. "We're about as close as we're going to get," Drake said.

I'm Bryan Lynn.

Bryan Lynn wrote this story for VOA Learning English, based on reports from the University of California, Berkeley, the University of Maryland and Nature.

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blast – v. an explosion or violent detonation

shower – n. a piece of equipment that shoots out water and is used to clean the body

source – n. where something comes from

practical – adj. able to be done successfully