Ursula Marvin was told to learn to cook. She read the Moon from its crumbs instead.

Harvard gave her a PhD in 1969. That same year John Wood's group at the Smithsonian Astrophysical Observatory, where Marvin worked, began sorting through Apollo 11 soil, rock fragments 1 to 2 millimetres across. The mineralogy and X-ray diffraction in the group's proposal were hers. Among the fragments was something unexpected: white, anorthosite-rich rock. The team concluded that anorthosite must have separated out in an early Moon that was largely or wholly melted. The lunar magma ocean hypothesis counts Marvin among its authors.

Later she looked for the Moon on Earth. Marvin was the first woman in the US meteorite recovery programme and spent the 1978–79 and 1981–82 seasons in Antarctica. She also wrote the authoritative description of the first lunar meteorite recognised from the south polar region. A peak in Antarctica carries her name, and so does a 4.6-kilometre crater near the Moon's south pole.

In 1997 she said discrimination had mostly passed her by. With one exception: after the Second World War the Harvard Geology Club wanted to go back to being all male. Marvin and her friends argued, the two sides settled on a "Ladies Night", and when the treasurer called for dues she was first in line. Two dollars. The club has admitted women ever since.