Published on Oct 6, 2015
NASA's SDO Sees a Huge Coronal Hole Spread out Over Almost the Entire Northern Hemisphere of the Sun.NASA's Solar Dynamics Observatory captured a picture of the sun on October 6, 2015, showing two huge coronal holes.
The larger coronal hole spread out over almost the entire northern hemisphere of the sun, covers an estimated 8 to 10-percent of the total solar surface, making it one of the largest polar holes scientists have observed in decades. Solar wind flowing from these two coronal holes should reach Earth on Oct 8-9.
A coronal hole is an area of the sun's atmosphere, the corona, where the magnetic field opens up and the material flows quickly out. This results in a cooler and less dense atmosphere than the surrounding areas.
Coronal holes spew out fast solar wind, probably traveling at about 400-500 miles per second. This is roughly twice the speed of the normal solar wind, the solar material that is constantly streaming off the sun in every direction to fill the solar system.
These images were taken by NASA's SDO solar spacecraft
http://sdo.gsfc.nasa.gov/data/
Images credit: NASA/SDO and SOHO
http://sdo.gsfc.nasa.gov/assets/img/l...
http://sohowww.nascom.nasa.gov/data/r...
Coronal hole
https://en.wikipedia.org/wiki/Coronal...
What is a coronal hole?
http://www.ips.gov.au/Educational/2/1/5
http://www.spaceweatherlive.com/en/he...
