This spooky looking aurora was seen near Nome, Alaska in October of 2003, just days before Halloween. Credit: Spaceweather.com

(麻豆淫院Org.com) -- By the eerie light of a Halloween moon, while a chilly wind blows autumn-dry leaves askitter on bare and fingered branches, scary things can happen. Blood-sucking bats, creepy-crawly spiders, and a bevy of Halloween horrors give a fright on October 31. But did you know the weeks surrounding this All Hallow鈥檚 Eve mark a haunting milestone? 鈥 the 5-year anniversary of some the most powerful solar storms ever recorded.

Called the "Halloween Storms of 2003," these energetic storms began, surprisingly, near the low point in the sun鈥檚 11-year cycle of solar activity. During this usually "quiet" time, when few sunspots are visible, an outbreak of 17 major flares erupted on the sun.

The flares caused the sun鈥檚 magnetic field lines to stretch then suddenly snap like a rubber band stretched beyond its limit. The result was coronal mass ejections, enormous explosions on the sun鈥檚 surface that can blast billions of tons of electrified gas and subatomic particles into space at speeds up to 5 million miles per hour. This 鈥榮pace weather鈥 can and does affect Earth.

Space weather from these enormous solar storms slammed into Earth鈥檚 magnetic field from October 19 through November 7. 鈥淭he effects of these storms were ghoulish enough that [aircraft controllers] had to re-route aircraft, it affected satellite systems and communications, and it also caused a power outage in Sweden for about an hour,鈥 said Dr. Holly Gilbert, a solar scientist at NASA鈥檚 Goddard Space Flight Center in Greenbelt, Md.

During the height of the solar activity, more than half of the deep space and near-Earth space science missions experienced the effects of the Halloween storms of 2003. The Solar and Heliospheric Observatory (SOHO) satellite, a collaboration between NASA and the European Space Agency (ESA), failed temporarily. NASA鈥檚 Advanced Composition Explorer (ACE) satellite experienced damage, and instruments aboard many spacecraft had to be shut down temporarily.

Another effect of these storms was an increase in the colorful dancing lights seen at Earth鈥檚 north and south poles, called aurora. 鈥淭he aurora are normally limited to the higher latitudes, and these storms were so powerful they created aurora that could be seen as far south as Florida,鈥 said Gilbert.

Scary solar storms like the Halloween storms of 2003 are the exception, rather than the rule. Preparing for sudden, severe space weather can help reduce the effects of storms like these. A future NASA mission, called the Solar Dynamics Observatory (SDO) will investigate the sun in great detail in an attempt to learn how changes on the sun impact Earth. The more sun-focused satellites learn about our nearest star, the better prepared we鈥檒l be the next time storms erupt on the sun.

Provided by NASA's Goddard Space Flight Center