The sun is obviously incredibly important for earth as it provides virtually all the energy to drive the climate and life itself. We have been studying the sun for a long time, but almost all those studies have been done from the ground, so we have had limited information of how the output of the sun changes in frequencies which don't make it through the atmosphere. These are particularly important for the upper atmosphere as if they are blocked by the atmosphere they will be heating it.
Up until now atmospheric modelers have assumed that as the sun's output changes through the 11 year solar cycle all the different wavelengths change together. But a NASA satellite called SORCE the Solar Radiation and Climate Experiment has been studying the changes in the sun since 2003. And this has found that all wavelengths are not the same, the amount of Ultra Violet varies ten times as much as the average and Infra Red changes much less.
This could explain much larger than expected changes in the temperature of the stratosphere over the solar cycle, as this contains the ozone layer which is absorbing the UV.
It may also mean that variability in the sun has much less of an effect on climate than was previously assumed and it will probably make climate modellers life more complicated.