Pluto’s unique interaction with solar wind revealed

Pluto (Photo Courtesy: NASA)

Washington – Pluto behaves less like a comet than expected and somewhat more like a planet like Mars or Venus in the way it interacts with the solar wind — a continuous stream of charged particles from the Sun, a first ever analysis has revealed.

Using data from the New Horizons flyby of Pluto last year, scientists have observed the material coming off of Pluto’s atmosphere and studied how it interacts with the solar wind, leading to yet another “Pluto surprise”.

“This is a type of interaction we’ve never seen before anywhere in our solar system,” said David J. McComas, professor of astrophysical sciences at the Princeton University.

According to space physicists, they now have a treasure trove of information about how Pluto’s atmosphere interacts with the solar wind.

Solar wind is the plasma that spews from the Sun into the solar system at a supersonic 160 million km per hour, bathing planets, asteroids, comets and interplanetary space in a soup of mostly protons and electrons.

Previously, most researchers thought that Pluto was characterized more like a comet which has a large region of gentle slowing of the solar wind as opposed to the abrupt diversion solar wind encounters at a planet like Mars or Venus.

Instead, like a car that is part gas-and part battery-powered, Pluto is a hybrid, researchers said.

“These results speak to the power of exploration. Once again we’ve gone to a new kind of place and found ourselves discovering entirely new kinds of expressions in nature,” added Alan Stern, New Horizons’ principal investigator.

Since it is so far from the Sun, scientists thought Pluto’s gravity would not be strong enough to hold heavy ions in its extended atmosphere.

But, “Pluto’s gravity clearly is enough to keep material relatively confined”, McComas noted.

Like the Earth, Pluto has a long ion tail that extends downwind at least a distance of about 118,700 km, almost three times the circumference of the Earth, loaded with heavy ions from the atmosphere and with “considerable structure”.

The findings, published in the Journal of Geophysical Research-Space Physics offer clues to the magnetised plasmas that one may find around other stars.