The average black working woman makes 63 cents for every dollar a white, non-Hispanic man makes. As a result, she’d have to work all of last year and up to today, to catch up. And she makes 21% less than her white, female counterpart.

The gap starts early and persists, explains my colleague McKenna Moore:

A data analysis of BusyKid’s app’s 10,000 users shows that parents pay boys a weekly allowance twice the size that they pay girls. By 16, black women are earning less than white men and the gap only widens as they age. As black women have families of their own, the gap means less money for their families, which is particularly harmful because more than 80% of black mothers are the main breadwinners for their households, according to the National Partnership for Women & Families.

It adds up. According to the National Women’s Law Center, this means that black women earn some $870,000 less than men over a 40-year career.

Yet, despite the best efforts of advocates to get the word out, this wage gap is still a surprise to many.

According to a survey by Survey Monkey, Lean In, and the National Urban League, one in three Americans don’t know about the pay gap between black women and white men, half don’t know about the pay gap between black women and white women; and nearly half of white men think that the barriers to black women’s advancement are gone.

You can’t manage what you don’t measure and you can’t fix what you don’t know is broke. But you knew that, too.

In an op-ed, Sheryl Sandberg, the COO of Facebook and founder of LeanIn.Org and OptionB.Org, and Laphonza Butler, the president of SEIU Local 2015 say that there are plenty of ways we can address the system at large:

There’s a lot we can do to close the pay gap—starting with raising the federal minimum wage, which would help increase the incomes of more than one in four black women in the workforce. Several states have taken steps to protect workers from retaliation when they discuss pay; the federal government should follow suit. At a time when labor rights are eroding, we need stronger protections for the millions of women who are proud union members—or want to be. And Congress must pass a national paid and family medical leave law. It would be particularly helpful to black women, too many of whom have to rush back to work after having a baby or put medical care for themselves on the back burner because they can’t afford to go days or weeks without a paycheck.

But there are things you can do right now to help.

Acknowledging workplace inequality, particularly when it doesn’t directly involve you, is something anyone can do. In fact, it’s one of the simplest, most powerful ways to be an ally.

So today, regardless of your race or gender, share some data, rock a hashtag, raise someone’s profile online, or simply ask a woman of color in your circle what’s she’s working on and how you can help.

You don’t have to pull off a full Jessica Chastain power move to make a difference. (Although it was a good one: Chastain recently insisted that she and her co-star Octavia Spencer, long undervalued in Hollywood, be paid the same salary on an upcoming film project.) All you have to do is cast a little light on someone else’s path. Then, let it shine, let it shine, let it shine.