FIGURE 2. An image of the solar photosphere (the surface of the solar disk seen in visible light), showing the structures responsible for the TSI variations.
From the following article:
Variations in solar luminosity and their effect on the Earth's climate
P. Foukal, C. Fröhlich, H. Spruit and T. M. L. Wigley
Nature 443, 161-166(14 September 2006)
doi:10.1038/nature05072
The granules, covering most of the area, are the convective flows carrying energy from the interior. They contribute the steady component of the irradiance received by the Earth. Magnetic structures are dark (sunspots) or bright (the small bright points called faculae) and contribute a component that varies with the sunspot cycle. Faculae show up especially towards the limb of the solar disk. Their contribution dominates over the dark spots, so that the Sun is slightly brighter at sunspot maximum. Scale bar, ten megametres. (Image taken with the Swedish 1-m Solar Telescope by B. De Pontieu on 16 June 2003.)
