  The Sun is a variable star whose magnetic activity varies most perceptibly on
a timescale of approximately 11 years. However, significant variation is also
observed on much shorter timescales. We observe a quasi-biennial (2 year)
signal in the natural oscillation frequencies of the Sun. The oscillation
frequencies are sensitive probes of the solar interior and so by studying them
we can gain information about conditions beneath the solar surface. Our results
point strongly to the 2 year signal being distinct and separate from, but
nevertheless susceptible to the influence of, the main 11 year solar cycle.
