WASHINGTON, Dec. 4 (Xinhua) -- The U.S. space agency NASA published its first batch of Parker Solar Probe results, showing never-seen-before details of the sun and providing clues to new solar physics.
The observations made by two record-breaking close flybys by NASA's Parker Solar Probe, launched to space in August 2018 and soon becoming the closest-ever spacecraft to the sun, revealed how the sun constantly ejects material and energy, according to four papers published online on Wednesday in the journal Nature.
"Observing the sun up close rather than from a much greater distance is giving us an unprecedented view into important solar phenomena and how they affect us on Earth, and gives us new insights relevant to the understanding of active stars across galaxies," said Thomas Zurbuchen, associate administrator for science at NASA.
One of the studies lent new insights into the processes that drive the solar wind, a constant outflow of hot, ionized gas that streams outward from the sun.
The strange magnetic field reversals called "switchbacks," which whips back on itself until it is pointed almost directly back at the sun, could be accelerating particles toward Earth, according to the study.
In a separate paper, the researchers found clues on how sun's rotation affects the outflow of the solar wind. Observing from about 32 million km from the sun, Parker made the first-ever observations of this effect: the solar wind near the sun rotates with the star before it travels in almost straight lines.
Parker found that the extent of this sideways motion was much stronger than predicted, but it transitioned more quickly than predicted to a straight, strictly outward flow. Understanding the transition point in the solar wind can help scientists understand how the sun's rotation slows down over time, thus revealing its life cycles, according to the study.
Also, Parker observed the periphery of elusive dust-free zone for the first time, providing direct evidence of dust starting to thin out around 11 million km from the sun.
Cosmic dust is expected to be heated to high temperatures by sunlight, turning into a gas and creating a dust-free region around the sun. Parker results showed that, closer to the sun, the dust continues to thin out. The truly dust-free zone starting a little more than three to five million km from the sun, which could be observed in Parker's sixth flyby.
In the fourth paper, the researchers described Parker's observations of two types of space weather events: energetic particle storms and coronal mass ejections.
A rare type of particle burst with a particularly high ratio of heavier elements was observed, according to the study. Solar energetic particle events can arise suddenly and lead to space weather conditions near Earth that can be potentially harmful to astronauts.
Parker's data also provided unprecedented detail on coronal mass ejections, billion-ton clouds of solar materials hurtling out into the solar system, according to the study.
Parker has completed three of 24 planned passes through the sun's atmosphere, the corona. It will culminate in three orbits a mere 6.16 million km from the solar surface.
"Observations near Earth have made us think that fine structures in the corona segue into a smooth flow, and we're finding out that's not true. This will help us do better modeling of how events travel between the sun and Earth," said Russ Howard from the U.S. Naval Research Laboratory.