Solar science

NASA probe sheds new light on the sun

Print edition : January 03, 2020

An illustration of the Parker Solar Probe. Photo: NASA

NASA’S Parker Solar Probe has shed new light on the previously unknown and only theorised characteristics of the sun. The probe, launched in August 2018 to study the sun up close and unlock the mysteries of its atmosphere, is designed to use Venus’ gravity during seven flybys over nearly seven years to gradually bring its orbit closer to the sun. (The average distance of the earth to the sun is about 150 million km.)

Parker is currently in its fourth orbit around the sun, and its present distance from the sun is about 126 million km. The closest to the sun that the spacecraft went during its initial flybys was 24.1 million km on November 6, 2018. This is already closer to the sun than Mercury is. The spacecraft will get even closer in the future, as it travels at more than 343,000 km/h, faster than any previous spacecraft.

The first results were published in a series of four papers in a recent issue of “Nature”. The four papers reveal new insights into the processes that drive solar wind—the constant outflow of hot, ionised gas that streams outward from the sun and fills up the solar system—and how the solar wind couples with solar rotation. The mission has also examined the dust of the coronal environment and spotted particle acceleration events so small that they are undetectable from the earth.

Seen near the earth, the solar wind plasma appears to be a relatively uniform flow, one that can interact with our planet’s natural magnetic field and cause space weather effects that interfere with technology. Instead of that flow, near the sun, Parker’s observations reveal a dynamic and highly structured system, similar to that of an estuary that serves as a transition zone as a river flows into an ocean. For the first time, scientists are able to study the solar wind from its source, the sun’s corona (the outermost part of its atmosphere), similar to how one might observe the stream that serves as the source of a river. This provides a different perspective compared with studying the solar wind where its flow impacts the earth.

The information Parker has uncovered about how the sun constantly ejects material and energy will help scientists rewrite the models they use to understand and predict the space weather around the earth and understand the process by which stars are created and evolve. This information will be vital to protecting astronauts and technology in space, according to NASA.

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