Henrietta Leavitt's Cosmic Yardstick

In 1895, Henrietta Swan Leavitt began work at the Harvard College Observatory. She was a 'computer,' one of several women hired by Director Edward Pickering to perform the painstaking calculations male astronomers were too busy for. Initially an unpaid volunteer, she was eventually hired at 30 cents per hour, less than half the salary of a man. Her task was to study variable stars, whose brightness fluctuates over time, by analyzing thousands of glass photographic plates. Leavitt undertook this meticulous work while suffering from progressive hearing loss that would eventually leave her profoundly deaf. She was assigned a specific patch of sky to study: a faint, fuzzy object known as the Small Magellanic Cloud.