The Starbow
In 1962 E. Saanger (Journal of the British Interplanetary Society {1962} 18{7}: 273-7) described the starbow like this:  
".…at 0.37c or faster a major dark spot will cover the take-off star and a minor dark spot the target star. Between these… all stars visible in the sky are coloured in all the hues of the rainbow, in circles concentric to the flight direction (like the picture below left).

However, Grant Hutchison (OIKOFUGE 27th June 2018, gives a realistic (maths based) description (to produce the picture lower right). Basically Saanger modelled all the stars as equally distributed and at one temperature (λ0 = 5900Å) whereas real stars are randomly distributed and come in a variety of colours. An excellent non-technical description can be found here: