The sun is heading toward solar minimum now. Sunspot counts were relatively high in 2014, and now they are sliding toward a low point expected in 2019-2020.
While intense activity such as sunspots and solar flares subside during solar minimum, that doesn’t mean the sun becomes dull. Solar activity simply changes form.
During solar minimum we can see the development of long-lived coronal holes.
Coronal holes are vast regions in the sun’s atmosphere where the sun’s magnetic field opens up and allows streams of solar particles to escape the sun as the fast solar wind.
We can see these holes throughout the solar cycle, but during solar minimum, they can last for a long time – six months or more. Streams of solar wind flowing from coronal holes can cause space weather effects near Earth when they hit Earth’s magnetic field. These effects can include temporary disturbances of the Earth’s magnetosphere, called geomagnetic storms, auroras, and disruptions to communications and navigation systems.
There are unique space weather effects that get stronger during solar minimum.
For example, the number of galactic cosmic rays that reach Earth’s upper atmosphere increases during solar minimum. Galactic cosmic rays are high energy particles accelerated toward the solar system by distant supernova explosions and other violent events in the galaxy.
Experts say that “During solar minimum, the sun’s magnetic field weakens and provides less shielding from these cosmic rays. This can pose an increased threat to astronauts traveling through space.”
Solar minimum brings about many changes to our sun, but less solar activity doesn’t make the sun and our space environment any less interesting.
Phys.Org
Read more at: https://phys.org/news/2017-06-solar-minimum.html#jCp
Clips, images credit: NASA, ESA/HUBBLE & ESO
Post time: Jul-05-2017