Measurements of ¹²C/¹³C in different molecules for several comets (for references see Table 3). Several measurements of ¹²C/¹³C in the coma of 67P were taken by ROSINA/DFMS. The coma of 67P shows an enrichment of ¹³C in CO₂ (black circle, this work) compared to solar abundance. For discussion on uncertainties see Sects. 4 and 5. The dotted horizontal line represents the terrestrial ¹²C/¹³C ratio. The solid horizontal line (dashed lines represent uncertainties) represents the solar wind ¹²C/¹³C ratio.