Long before they could vote, the women known as the Harvard Computers shaped our understanding of the universe with their prolific and precise astronomical calculations. Among them was Henrietta Swan Leavitt (July 4, 1868–December 12, 1921), who singlehandedly measured and catalogued more than 2,000 variable stars — stars that pulsate like lighthouse beacons. Along the way, she discerned a correlation between their brightness and their blinking pattern that soon allowed astronomers to measure the distance of stars for the first time, furnishing the yardstick of the cosmos. Her insight made it possible to determine the size of the Milky Way and the age of the universe. It was foundational to Edwin Hubble’s groundbreaking discovery of the existence of other galaxies and the expansion of the universe.

Leavitt’s trailblazing life and legacy come alive in Look Up! (public library) by poet, essayist, and children’s book author Robert Burleigh, consummately illustrated by artist Raúl Colón — a delightful addition to the finest picture-book biographies of visionaries.

The story begins with Henrietta as a little girl who, like Vera Rubin, is about to turn her passion for stargazing into a lifetime of revolutionary astronomy.

Night after night, Henrietta sat on her front porch, gazing up at the stars.
How high?
How high is the sky?

As she grows up, the enchantment of the night sky never leaves her. It becomes more than a pastime, more than a passion — it becomes a calling.

She wanted to know everything about the wonderful bigness of all she saw. The more she looked up, the bigger the sky seemed to get.

We see her as the only young woman in an astronomy classroom of men — a hard-won achievement barely a generation old by then, made possible by the visionary astronomer Maria Mitchell, who paved the way for women in science not long before Henrietta was born. (Mitchell is the subject of another lovely picture-book biography.)

We see her graduate to join the Harvard College Observatory, working for thirty cents an hour alongside the other women computers, so consumed with her stars that they come to animate the nocturne of her mind even when asleep.

As she obsessively studies each night’s photographs, measuring the stars with a magnifying glass in hand, she begins noticing subtle differences between their brightness across the different images — a blinking pattern revealing how much light, or power, a star contains.

With the speed of light known for more than two centuries, it was now suddenly possible to measure how far the star is from Earth — proof that “the smallest observation, the tiniest discovery, often leads to something very important.”

Complement Look Up! with poet Anna Leahy’s stirring ode to Henrietta Leavitt and the illustrated story of Edwin Hubble, whose epochal discovery was winged with Leavitt’s work, then revisit other wonderful picture-book biographies of visionaries who shaped our world: Corita Kent, Keith Haring, Maria Mitchell, Ada Lovelace, Louise Bourgeois, Wangari Maathai, Virginia Woolf, Galileo, Nellie Bly, Paul Erdos, Louis Braille, Mary Lou Williams, John Lewis, Muddy Waters, Paul Gauguin, and Jane Jacobs.