The 'Big Dipper' or 'Plough' is a star formation in the night sky whose distinctive shape has been recognised and noted in many different cultures.
It consists of the seven brightest stars of the constellation Ursa Major, which is also known as the 'Great Bear'.
'Cassiopeia' is a W-shaped northern constellation which in Greek mythology is said to represent the queen Cassiopeia.
'Cassiopeia's Chair' consists of the five or six brightest stars in the constellation that are sometimes said to form the shape of a chair.
In the picture above, astronomy buffs may be able to locate the 'Big Dipper' (somwhere on the left) and 'Cassiopeia' (somewhere on the right). The rest of us may just have to acknowledge, like Esther Greenwood, that we're 'hopeless at stars'.