Solar cycle 23 is the 23rd solar cycle

Solar cycle

The solar cycle, or the solar magnetic activity cycle, is a periodic change in the amount of irradiation from the Sun that is experienced on Earth. It has a period of about 11 years, and is one component of solar variation, the other being aperiodic fluctuations. Solar variation causes changes in...

 since 1755, when recording of solar sunspot

Sunspot

Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature....

activity began. The solar cycle lasted 12.6 years, beginning in May 1996 and ending in December 2008. The maximum smoothed sunspot number (monthly number of sunspots averaged over a twelve month period) observed during the solar cycle was 120.8, and the minimum was 1.7. There were a total of 805 days with no sunspots during this cycle.

One of the first major aurora displays of solar cycle 23 occurred on April 6, 2000, with bright red auroras visible as far south as Florida and South Europe. On July 15, 2000, a strong G5 geomagnetic storm (the Bastille day storm) caused damage to GPS systems and in some power companies. Auroras were visible as far south as Texas. Another major aurora display was observed on April 1, 2001, due to a coronal mass ejection hitting the Earth's magnetosphere. Auroras were observed as far south as Mexico and South Europe. The following day, a very large solar flare occurred on April 2, 2001 (X20) but the blast was directed away from Earth. In late October 2003, a series of large solar flares occurred. A X17 flare on October 28, 2003 (X17) resulted in auroras visible as far south as Florida and Texas. A few days later, the largest solar flare ever measured with instruments occurred on November 4, 2003 (initially measured at X28 and later upgraded to X45). This flare was not Earth-oriented and thus only resulted in high-latitude auroras. Another large solar flare occurred on September 7, 2005 (X17) with auroras visible in mid-latitudes.

A complete list of the larger solar flares of this cycle is available at spaceweather.com