New data from the New Horizons spacecraft, which collected three years worth of data while sampling its surroundings on the way to Pluto, shows how changes in the behavior of the solar wind affect the space environment throughout the Solar System.
The Solar Wind Around Pluto or SWAP instrument is designed to study the solar wind—a steady stream of charged particles emanating from the Sun—and gave scientists the chance to test current space weather models, like the visualization seen above.
This model shows the space environment a few months before the spacecraft's closest approach to Pluto. "Drawn over the model is the path of New Horizons up to 2015, as well as the current direction of the two Voyager spacecraft—which are currently at three or four times New Horizons' distance from the sun. The solar wind that New Horizons encountered will reach the Voyager spacecraft about a year later," NASA writes.
The findings, published in the Astrophysical Journal Supplement, will help scientists understand space weather by filling in the gaps between what we know from missions closer to the Sun and what we've learned from the Voyager spacecrafts.
We think of space as being empty; however, it's not completely devoid of matter. Solar wind fills the void with a steady supply of charged particles, and ionized gas, called plasma. Frequently, large clumps of solar material explode into space in the form coronal mass ejections or CMEs. These fast-moving clumps of material cause shock waves which can produce space weather, like the dazzling aurorae we see on worlds with magnetic fields.
As the Sun rotates, it shapes the solar wind into observable patterns, that start out as exaggerated structures, and flatten out or merge as they propagate through space. In the visualization, temperature, density, and pressure are represented by the colors red, green, and blue. Density of the solar wind decreases as it travels through the solar system while temperature remains constant. A key is here.
New Horizons also spied what could be the birth of anomalous cosmic rays: a type of radiation—which is harmful to both spacecraft and astronauts—formed when energetic particles in the solar wind collide with interstellar medium. The Voyager probes observed these rays, but never their formation.
"There are similar characteristics between what was seen by New Horizons and Voyager 2, but the number of events is different," lead author Heather Elliott explained in a press release. "Solar activity was much more intense when Voyager 2 traveled through this region."