Workers will be taking a lot of time off on Monday to see this astronomical event

This is one expensive eclipse — even if you’re not buying any special glasses to wear for the occasion. The “Great American Eclipse” on Aug. 21 will be especially clear for Americans in Oregon, Idaho, Wyoming, Tennessee and South Carolina. A solar eclipse was last viewable on a path that crosses the entire country in 1918.

Here’s the Debbie Downer side of this once-in-a-lifetime event: The eclipse will happen during the workday, and many workers will likely try to watch it. As a result, it will cost employers some $694 million collectively, according to an analysis from Challenger, Gray & Christmas, a firm based in Chicago that specializes in helping employees transition in their careers. The company did not even factor in the employees that might be taking time off to actually travel to watch the eclipse, if they don’t live in its direct path.

Workers will need about 20 minutes to gather any viewing equipment they’ll use and to watch the eclipse, which itself will only take about two minutes, Challenger calculated. Nearly 83% of people go to work on an average weekday based on Bureau of Labor Statistics data. Using those figures, along with the average hourly national wage and the number of full-time employed workers 16 and over, the firm found how much the 20-minute loss of work could cost.

The eclipse will also bring in tens of millions of tourist dollars. The city of Nashville estimates some 50,000 to 75,000 people will visit, spending a total of $15 million to $20 million during the eclipse, according to USA Today. And tourism revenue could be as high as $43 million in South Carolina. An estimated 100,000 people are expected to visit Salem, Ore., and Southeastern Idaho may see as many as 300,000 to 500,000 visitors, tourism organizations in those places told USA Today.

The eclipse isn’t the only event that costs the U.S. workplace, and certainly won’t be the most expensive for employers. Every year, the March Madness college basketball tournament costs workplaces nearly $2 billion, according to Challenger. That’s based the assumption that around 80 million workers spend one hour on average on March Madness, including filling out and updating brackets and watching games or checking scores.

And the eclipse pales in comparison to all the other distractions. In addition to answering personal emails and texts on smartphones, online shopping, and watching sports, employees report spending 42 minutes on other personal tasks. This adds up to 8 hours a week, and $15.5 billion in lost productivity, a recent study by staffing firm OfficeTeam found.

This year, ketchup-maker Heinz KHC, -1.61% gave its full-time salaried workers a day off after the Super Bowl. The Monday after the game “is one of the worst days of the year,” the company’s head of brand told “Advertising Age” magazine. Heinz even started a petition to make the day a national holiday, since so many workers call in sick or are unproductive at work.

That said, Challenger isn’t suggesting U.S. workers become slaves to capitalism rather than watch the eclipse.Companies could use the eclipse “to increase morale and strengthen the team,” said Andrew Challenger, the company’s vice president, in a statement. “Building in time around lunch to mark the special occasion will encourage employees to interact and have something to be excited about.”