Onset of Next Solar Activity Cycle Observed
A new telescope installed in 2004 at Kitt Peak, Arizona, to monitor the next two cycles of solar activity has recorded the onset of the next solar cycle.
Solar cycle 23, now waning, was relatively weak and some predictions are that Cycle 24 will be considerably stronger. Such predictions are difficult because little is known about what governs the strength of the cycles, or when they may appear. A fast rise of activity may be a sign of a pending strong cycle.
Indicators of the new cycle were recorded by the Vector Spectromagnetograph (VSM), one of three instruments making up the Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility built by the National Solar Observatory (NSO) for the National Science Foundation (NSF). The Association of Universities for Research in Astronomy operates SOLIS as part of the NSO under a cooperative agreement with the NSF.
Solar activity and its effects on Earth wax and wane in an 11-year cycle generally characterized by the number and intensity of sunspots and flare events. Minimum activity is predicted to occur around February 2007. Early signs of Cycle 24 have been observed by the NSO as early as June and were announced at the annual meeting, of the Solar, Heliospheric and Interplanetary Environment (SHINE), a community-based program sponsored by the NSF. The meeting was held July 31-Aug. 4 in Midway, Utah.
The variation of solar activity drives conditions throughout the solar system and in the space near Earth. It is also responsible for geomagnetic storms that can cripple communications and damage power grids. Understanding the causes of the solar cycle is a major goal of solar research.
The SOLIS VSM began operation in 2003 and replaced the Vacuum Telescope in 2004 when it was installed by NSO at the Kitt Peak, AZ, site. The Vector Spectromagnetograph has outstanding sensitivity to the magnetic fields that erupt at the solar surface and which cause solar activity. Solar astronomers discovered some 80 years ago that these eruptions have an east-west orientation that reverses magnetic polarity with each new cycle, thus making a 22-year cycle. New cycle activity also shows up first at high latitudes, towards the poles, before migrating towards the equator during the cycle. These two facts were exploited at NSO to discover small magnetic eruptions that belong to the new cycle beginning in June.
NSO researchers are continuing to use the new telescope to help understand the properties of the solar activity cycle. Additional instruments are the Full Disk Patrol Telescope and the Integrated Sunlight Spectrometer.
An image to accompany this story is on line at http://solis.nso.edu/news/Cycle24.html
