Conversation so far:
when was the safety car introduced in formula 1 races
The first safety car in Formula One was used at the 1973 Canadian Grand Prix, where a yellow Porsche 914 was called for duty following various weather related incidents.
what is the aim of a safety car in formula 1 races
The safety car comes into use during a race when the Race Director wants to reduce speed for safety reasons, like after an accident or heavy rain

Question: what are the green lights for
Self-contained rewrite: what are the green lights for in a formula 1 safety car