Washington: We imagine the Sun as a giant burning furnace that brings sunlight to us but NASA's Solar Dynamics Observatory (SDO) has spotted two huge holes on its surface called "coronal holes". "Coronal holes" are the source of a high-speed wind of solar particles that streams off the Sun some three times faster than the slower wind elsewhere. These solar winds can not only create geomagnetic storms on the Earth which can disturb communications in all forms but also affect astronauts' on deeper space mission like Mars in the near future. The holes are less dense and have lower temperature than the rest of the Sun's surface. One of them is the biggest seen in decades which is about "six-eight percent of the total solar surface". "While it is unclear what causes coronal holes, they correlate to areas on the Sun where magnetic fields soar up and away, without looping back down to the surface, as they do elsewhere," said Karen C Fox and Steele Hill of NASA's Goddard Space Flight Center. Coronal holes are low-density regions of the sun's atmosphere, known as the corona. Because they contain little solar material, they have lower temperatures and thus appear much darker than their surroundings. Coronal holes are visible in certain types of extreme ultraviolet light, which is typically invisible to our eyes. "These 'coronal holes' are important to understanding the space environment around the Earth through which our technology and astronauts travel," NASA said in a statement.