It’s a bummer that we missed this bulletin earlier in the week, but since it’s never too late to be annoyed about gender-based pay disparities, we’ll make the announcement a little late: Tuesday was Equal Pay Day, marking “how far into the year the average woman must work to earn as much as a man earned by the end of the previous year.”

Translation, in the words of Washington Post columnist Amy Joyce: “As has been true for about a decade, women earn only 77 cents for every dollar men make.”

That stat is an oldie, but it only gets more astonishing with age — time keeps ticking by, and the wage gap remains more or less the same. Joyce quotes economist and former Massachusetts Lt. Gov. Evelyn Murphy recalling that droves of women entered the workforce and received lesser wages in the ’60s, but everyone figured it was “just a matter of time till we caught up.” While today’s 77-cent average is a big improvement over the 59 cents to a man’s dollar women made back when Murphy graduated from college, the notion that women will catch up eventually seems to have fallen prey to Zeno’s Paradox.

Murphy emphasizes that the 23-cent disparity is based on the salaries of full-time working men and full-time working women. She also notes that while some suggest women’s lifetime earnings are lower because they take time off to raise their children, that theory rests on the assumption that most women can afford to take time off when their babies are born, when in fact many women cannot. Murphy asserts that the wage gap will only close when CEOs agree to review their company rosters and correct for gender-based pay disparities — making information campaigns like Equal Pay Day all the more vital.

To get really riled up, check out the calculators and fact sheets at Murphy’s Wage Project Web site and at the site for the National Committee on Pay Equity. There, you can compare your income with that of men working in your field and geographic area, chart the history of the wage gap and learn about the particularly egregious pay disparities faced by women of color.