What are the lights on curling stones? Why Winter Olympics 2022 stone has a green light on and what it means

Curling is one of the few Winter Olympic disciplines in which Great Britain generally carry a consistent medal hope.

Widely understood to have been invented in Scotland in the early 16th century, the sport is one that owes its heritage to that early act of sliding rocks on icy ponds, but the modern game has made huge technological strides over the past 500 years.

Even in the present day, advances are being made to improve the event, and spectators tuning in to catch any of the action from Beijing this week may have noticed that the stones used by athletes now have small electronic lights on them.

But why are they there and what purpose do they serve?

Here’s everything you need to know...

What are the lights on curling stones?

Viewers may have noticed that the curling stones in use during these Winter Olympics are fitted with a pair of red and green lights on either side of the handle.

Essentially, the lights act as a tracking system to ensure that athletes release their stone before crossing the first hog line.

The hog line is the red line at the end of the ice, and it is a violation for competitors to cross it with the stone still in their grasp.

A heat sensor is embedded into the ice which is triggered if an athlete’s hand continues to hold onto the handle of the stone while crossing the line.

Each stone contains batteries to power the sensors, and if it is not released in time then the inbuilt lights turn from green to red and the offending team will have to remove their stone as a penalty.

While it is rare for Olympic athletes to commit a hog line violation, it is not unheard of.

Already in Beijing we have seen Italy’s Stefania Constantini penalised in her country’s match against Team USA after holding on to a stone for too long in the sixth end.

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