Long-time listeners of CBC Radio should be able to recite the following phrase in their sleep: "Now from Ottawa, the National Research Council official time signal. The beginning of the long dash will indicate exactly 12 o'clock, Central Standard Time."

Today, the long dash is celebrating a birthday.

The official time signal turns 75 today. CBC Radio first broadcast the signal November 5th, 1939, as the country was fighting World War II.

"I remember it from when I was a kid," said John Bernard, Discipline Lead for the National Research Council's Frequency and Time group. "Back in the older days, before we had cell phones and probably more accurate time available to us, it was probably one of the major sources to set our watch accurately."

According to the research council, the official time signal is extremely accurate, down to around 100 nanoseconds of the international standard.

The council uses a system of atomic clocks that measure atoms from cesium, a radioactive element. Those atoms vibrate at a very consistent rate, making them an excellent way to tell time.

So, why go to the trouble of telling everyone exactly what time it is, down to the millisecond?

"High frequency trading in the stock market is starting to demand very high accuracy time," said Bernard. "Power plants have to synchronize so that they're all in sync with each other."

As for the future, it doesn't look like the long dash is going anywhere.

"It's our most visible form of dissemination that we do," he said.

On mobile? Here's our poll question about the time signal.