Long description

The image shows two images of the galaxy NGC 6964, captured at different wavelengths.

The left-hand image shows the galaxy in visible light. A label reads ‘visible’. It shows a well-defined, face-on spiral structure, with a bright core at its centre. A large expanse of dark sky surrounds the galaxy, which is dotted with foreground stars from the Milky Way.

The counterpart image (on the right-hand side) is labelled ‘radio (21 cm)’. The emission is dominated by the spiral structure of the galaxy. However, this spiral structure extends far beyond what can be seen in the optical image, into the regions where the optical image is dark.