US companies may lose upto $700 million due to lost productivity as employees put aside their work to witness the once-in-a-century solar eclipse, according to a top business person.

Workers took at least 20 minutes on Monday to watch the solar eclipse, Andy Challenger, vice president of Challenger, Gray and Christmas, an outplacement firm, said.

The rare astronomical event, known as Great American Eclipse, was observed throughout the whole country, and a total solar eclipse was witnessed in 14 states, reports Xinhua news agency.

“There are very few people who are not going to walk outside when a celestial event of such kind takes place,” Challenger said, estimating that 87 million employees were working during the eclipse.

To get the cost for employers, Challenger multiplied the figure of working employees by the estimated watching time and the average hourly wages estimated by the Bureau of Labour Statistics.

“Compared to the amount of wages being paid to an employee over a course of a year, it is very small,” Challenger said. “It’s not going to show up in any type of macroeconomic data.”

The US mainland has not seen a total solar eclipse since 1979, when it swept a handful of northwestern states. The country’s last total solar eclipse stretching from coast to coast took place in 1918.

This time, US space agency NASA provided a live webcast of the event, using 11 spacecraft, at least three NASA aircraft and more than 50 high-altitude balloons.