
She was observing the morning sky from Nantucket with a small telescope, noticed a faint fuzzy object that moved compared to nearby stars over several nights, recognized it as new, and reported it to other astronomers.
Maria Mitchell was 29 years old when she discovered the comet in 1847.
The Maria Mitchell Association in Nantucket preserves her story and runs programs, and reliable biographies are available at sites like Britannica and Wikipedia. Vassar College also holds historical information about her work.
Maria Mitchell never married. She devoted her life to astronomy, teaching, and encouraging women to study science.