Nasa's Parker Solar Probe, which has flown closer to the sun than any other spacecraft to date, beamed back its first observations from the edge of the sun's scorching atmosphere. Over the next six years, the car-sized spacecraft will follow an ever-closer orbit, eventually technically “touching” the sun. NASA's first data from the probe offers clues to long-standing mysteries, including why the sun's atmosphere, known as the corona, is hundreds of times hotter than its surface, as well as the precise origins of the solar wind.
Successful Parker Solar sample
“The first three encounters with the probe that we have had so far have been spectacular.” This is what Prof. Stuart Bale, a physicist at the University of California at Berkeley, said. He evaluated the analysis of one of the instruments of the craft. “We can see the magnetic structure of the corona, which tells us that the solar wind emerges from small coronal holes. We see impulsive activity, large jets or serpentines, which we believe are related to the origin of the solar wind. We are also surprised by the scale of the dust environment.”
Over the next six years, the car-sized spacecraft will follow an increasingly narrow elliptical orbit. Eventually it will hover so close that it can technically touch the sun. One downside to proximity, however, is that Parker Solar Probe doesn't send images home. If this were to be panned towards the sun, the camera would melt. In addition, the spacecraft's instruments look to the side and measure the flow of supersonic charged particles that make up the solar wind.
Surprising results
Previously, scientists observed that the sun's wind appears to have two main components. The first is a "fast" component that travels at a speed of 700 km/s and comes from huge coronal holes in the Sun's polar region. The second is a “slow” one that spreads at less than 500 km/s. However, their origin is still unknown. The Parker Solar Probe attributed the slow wind to small, coronal holes around the Sun's equator. So these are solar structures that NASA researchers have not observed before. Coronal holes are cooler, less dense areas. Magnetic fields flow through these into space and serve as channels for the flow of charged particles.
Another surprise was the dustiness of the area near the sun. During its closest approach to orbit, the probe was littered with fine dust, breaking off tiny pieces of its heat shield that appeared as white streaks in images captured by the high-resolution camera. They are believed to be the remnants of asteroids and comets that approached the Sun, causing them to evaporate, leaving only a dusty haze.
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