NASA’s Solar Dynamics Observatory released an image showing a dark area across the top of the sun called the coronal hole. The hole also known as dark spot is about 50 times the size of Earth, and its magnetic field can send out coronal material, causing high-speed solar wind stream.
Though the high-speed solar wind is harmless to humans on earth, it can disrupt satellite communications and some high-altitude radio signals. This coronal hole on the sun’s surface caused aurora on Earth, earlier this month. Solar dynamics Observatory said that the image was taken on October 10 in wavelengths of 193 Angstroms. Usually, coronal holes are formed over the sun’s pole and lower altitudes when the sun is less active during its 11-year cycle.
This coronal hole in the sun’s outer layer has become cooler and lower-density than the rest of the corona, adding to the weakened magnetic field that results in the easy release of charged particles and plasma in the solar wind. These solar storms can create geomagnetic storms on Earth, affecting radio communications and navigation systems.
The sun’s coronal holes can also cause aurora which makes the northern lights seen much further south than usual. Officials at National Oceanic and Atmospheric Administration (NOAA) said that the solar winds will continue to be strong as it continues way westward on the sun’s surface.
NOAA officials also predicted that auroras will be visible as far down as Pennsylvania, Iowa and Oregon, and bright auroras would continue around the Arctic Circle. Based on observations from the Tihany Magnetic Observatory in Hungary, the indices used by scientists are unable to detect some of the sun’s geomagnetic perturbations, which could pose a risk to power supply and communication networks. The image of the coronal hole was taken at an ultraviolet wavelength, and cannot be seen by the naked eye.[ Source ]