Artist’s impression of the evolution of the shell as deduced from the observations made in the mid-infrared (in the visible, it is almost opaque), using ESO’s Very Large Telescope Interferometer. The sequence starts on 28 February, i.e. about 20 days after the nova erupted. At that time, the material of the ejecta starts to cool and to condense. On 13 March, dust forms, obscuring the source, which is no longer detectable at visible wavelengths. This shell, initially opaque, will expand and dilute itself, while the inner regions continue to produce dust. The outer zones become transparent but a new shell of dust is formed at the end of the sequence, and can be seen as a bright circle. Because of this, the nova further dims for a few additional months.