Easily transportable, hangings like this one would have been used as visual aids for popular scientific lectures, held at various locations.
The Working Men's Educational Union was a philanthropic society founded in 1853, for ‘the elevation of the working classes, as regards their physical, intellectual, moral, and religious condition’. Their chief means of achieving this was to encourage popular literary and scientific lectures, ‘by preparing suitable Diagrams and other aids to lecturers’.
Star clusters are groups of stars that are bound by gravity. Globular clusters are made of hundreds of thousands of old stars. More loosely associated, open clusters contain a few hundred of young stars.