Massive Coronal Hole Across the Face of the Sun to Blast Earth with Solar Wind

NASA’s Solar Dynamics Observatory has photographed a massive coronal hole gaping across the face of the sun. It sounds like something from cosmic horror: A gaping black gash opens in the face of the sun like a solar wound and lets out a stream of strange material. Yet coronal holes aren’t an uncommon phenomenon.

The shifting hole photographed by NASA’s Solar Dynamics Observatory in orbit around the sun on June 11 is spectacular. At over 50 times the diameter of Earth at its widest point, it’s one of the largest ever seen by the observatory.

A coronal hole isn’t actually a hole in the sun. It’s a comparatively colder region in the plasma aura that surrounds the sun. In X-ray and extreme ultraviolet images, these regions appear black.

Coronal holes appear most often as the sun emerges down from solar maximum, the period during sun’s 11-year activity cycle during which it is most active, with sunspots and flares at peak. The most recent solar maximum peaked in 2014. The minimum, with few sunspots and flares, is expected around 2019.

The hole is a region that is low in energy and gas. This causes the magnetic fields to fall away from those regions, resulting in lower density plasma. This, in turn, allows high-speed solar winds to escape from the sun. When these blast toward the Earth, they result in geomagnetic storms.

When the solar wind collides with the Earth’s magnetosphere, the magnetic field of the solar wind and the Earth’s magnetic field interact, and a transfer of energy occurs. This creates one of Earth’s most spectacular phenomena: the aurora, a light show that danced across the sky.

Coronal holes typically last for several months, shifting around the surface of the sun, changing shape. 

Geomagnetic storms can cause a few problems for humans on Earth. The particle activity in the magnetosphere can interfere with radio and radar communications, as well as GPS devices.

QUIET WITH A CHANCE OF FLARES: Solar activity remains low. However, formerly tiny sunspot AR2552 is growing. It is now wider than Earth and has developed an unstable ‘beta-delta’ magnetic field that poses a threat for moderately strong explosions. NOAA forecasters estimate a 10% chance of M-class flares on June 11th.

Source: 

http://spaceweather.com/

http://www.solarham.net/

Clips, images credit: NASA’s SDO
http://sdo.gsfc.nasa.gov/