Coronal Holes

Coronal holes are large regions in the corona that are less dense and cooler than surrounding areas. The open structure of their magnetic field allows a constant flow of high-density plasma to stream out of the holes. There is an increase in the intensity of the solar wind effects on Earth when a coronal hole faces us.

The x-ray image above shows the Sun as viewed by the Yohkoh satellite. A large coronal hole, extending from the northern into the southern solar hemisphere is near the Sun's center. The brightest region shows hot loops that remain after a solar flare.

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December 15, 2008: SABER reveals the upper atmosphere's "breathing" pattern, in rhythm with the Sun -- NASA
September 27, 2007: Hole in the Sun -- APOD
February 19, 2007: Surprises from the Sun's south pole -- European Space Agency
February 7, 2007: South pole flyby -- Science@NASA
April 4, 2006: Coronal holes, jets, and the origin of 3He-rich solar energetic particle events -- ACE News
April 22, 2005: Solar wind originates in coronal funnels -- Max Planck Society
March 18, 2003: Coronal holes on the Sun -- NASA GSFC APOD
January 30, 2003: Environmental satellite readied to detect solar storms -- NASA GSFC
October 31, 2002: Spooky auroras light up autumn nights -- CNN.com
February 7, 2002: Coronal hole -- NASA GSFC APOD
October 16, 2001: Solar wind discoveries at solar maximum -- Spaceflight Now
March 3, 2000: The Sun's show hots up -- BBC News
March 2, 2000: Polar substorm -- NASA MSFC
February 24, 2000: Leaky Sun threatens disruption -- BBC