New Horizons Data Shows Solar Wind Slows 13% to 15% by 58 AU
Updated
Updated · Gizmodo · Jun 30
New Horizons Data Shows Solar Wind Slows 13% to 15% by 58 AU
3 articles · Updated · Gizmodo · Jun 30
Summary
A new Astrophysical Journal study found solar wind measured by NASA’s New Horizons was 13% to 15% slower at 58 AU, revealing a gradual slowdown before the heliosphere’s termination shock.
Simulations tied that drag to ionized interstellar atoms building up in the outer heliosphere; without that material, modeled wind speeds stayed well above what New Horizons actually recorded.
Voyager 2 and New Horizons showed a smaller 5% to 10% slowdown between 30 and 43 AU, suggesting the effect strengthens with distance rather than reflecting only the Sun’s weakening influence.
New Horizons is now about 66 AU from the Sun—roughly halfway to interstellar space—giving scientists a way to track conditions before the dramatic 56% solar-wind drop Voyager 2 saw at termination shock.
The findings could sharpen models of heliosphere boundaries that regulate galactic cosmic rays, improving radiation-risk estimates for future deep-space spacecraft and astronauts.
With our solar wind slowing unexpectedly, what does this reveal about the interstellar space New Horizons is about to enter?
As interstellar particles brake our solar wind, how does this change the radiation threat for future human missions beyond Mars?
How will IMAP's data from Earth's orbit help predict the cosmic ray dangers that deep-space Artemis missions will face?
New Horizons Reveals Major Solar Wind Deceleration at the Solar System’s Edge: Implications for the Heliosphere and Astrospheres
Overview
NASA's New Horizons spacecraft has confirmed that the solar wind slows down much farther from the Sun than previously observed, with new data showing a 13%–15% deceleration at 58 AU. This slowdown, detailed in a recent study, happens as the solar wind interacts with interstellar neutral atoms, which are picked up and gradually drag on the flow of charged particles. These findings provide strong evidence for long-standing theories about the outer heliosphere and reveal how the solar wind changes as it moves toward the edge of our solar system and meets the interstellar medium.