Square dance square dance, very rarely are two modern Western dances ever alike. Like traditional square dancing, recovering from occasional mistakes is often part of the fun. Dancers are encouraged to dance only those programs at which they are reasonably proficient, the default level of achievement being the Mainstream program. All programs are set by Callerlab, the callers' international association, which also governs the training of callers. Irish and Scottish dances are normally done to traditional tunes. English dances may be done to traditional tunes, though, especially at ceilidhs, there is experimentation with many different musical styles. The two types of American
Solar activity and climate the measurements started in 1978. Solar irradiance before the 1970s is estimated using proxy variables, such as tree rings, the number of sunspots, and the abundances of cosmogenic isotopes such as Be, all of which are calibrated to the post-1978 direct measurements. Solar activity has been on a declining trend since the 1960s, as indicated by solar cycles 19-24, in which the maximum number of sunspots were 201, 111, 165, 159, 121 and 82, respectively. In the three decades following 1978, the combination of solar and volcanic activity is estimated to have had a slight cooling influence. A 2010 study