Far out cosmology: solar system boundary protects us (Introduction)

by David Turell , Tuesday, October 11, 2022, 14:59 (560 days ago) @ David Turell

Beyond of our sun's protection cosmic rays are dangerous:

https://www.sciencealert.com/strange-ripples-have-been-detected-at-the-edge-of-the-sola...

"The bubble of space encasing the Solar System might be wrinkled, at least sometimes.

"Data from a spacecraft orbiting Earth has revealed ripple structures in the termination shock and heliopause: shifting regions of space that mark one of the boundaries between the space inside the Solar System, and what's outside – interstellar space.

"The results show that it's possible to get a detailed picture of the boundary of the Solar System and how it changes over time.

"This information will help scientists better understand a region of space known as the heliosphere, which pushes out from the Sun and shields the planets in our Solar System from cosmic radiation.

"There are a variety of ways the Sun affects the space around it. One of those is the solar wind, a constant supersonic flow of ionized plasma. It blows out past the planets and the Kuiper Belt, eventually petering out in the great emptiness between the stars. (my bold)

"The point at which this flow falls below the speed at which sound waves can travel through the diffuse interstallar medium is called the termination shock, and the point at which it is no longer strong enough to push back against the very slight pressure of interstellar space is the heliopause.

"Both Voyager probes have crossed the heliopause and are, effectively, now cruising through interstellar space, providing us the first in situ measurements of this shifting boundary. But there's another tool out in Earth orbit that has been helping scientists map the heliopause since it commenced operations in 2009: NASA's Interstellar Boundary Explorer (IBEX).

"IBEX measures energized neutral atoms, which are created when the Sun's solar wind collides with the interstellar wind at the Solar System boundary. Some of those atoms are catapulted further out into space, while others are flung back at Earth. Once the strength of the solar wind that produced them is taken into account, energized neutral particles that return our way can be used to map the shape of the boundary, a bit like cosmic echolocation.

"Previous maps of the structure of the heliosphere have relied on long-scale measures of the evolution of solar wind pressure and energetic neutral atom emissions, which resulted in a smoothing of the boundary in both space and time. But in 2014, over a period of roughly six months, the dynamic pressure of the solar wind increased by roughly 50 percent."

Comment: the rest of the article describes heliosphere boundary measurements. What I find interesting is how the sun's solar wind stops cosmic rays and protects us.