Matt Damon

The most important thing Matt Damon ever wrote started as homework. In a playwriting class at Harvard he turned in a few dozen pages about a janitor at MIT with a gift for mathematics and a talent for pushing people away. He and Ben Affleck, his friend since Damon was ten and Affleck eight, living two blocks apart in Cambridge, kept expanding it. The result was Good Will Hunting, and in 1998 the two of them walked onstage to collect the Academy Award for Best Original Screenplay.

That story says a lot about how Damon works: through partnership, over a long time, with people he trusts. His chart, cast for 3:22 p.m. on October 8, 1970, in Cambridge, Massachusetts, a time taken from his birth certificate, leans the same way. His Sun is in Libra, the sign of balance and collaboration, and it sits in the eighth house, the zone astrologers tie to shared resources, joint ventures and what people build together. Mercury and Uranus are there with it. It is a chart less interested in solo glory than in the pooled effort, which is close to a description of the screenplay that made him.

He grew up in Cambridge, went to Cambridge Rindge and Latin School, where classmates remembered him and Affleck as drama kids, and studied English at Harvard before leaving short of a degree to act full time. The breakthrough brought a run of serious films, then a franchise nobody quite expected from him. As Jason Bourne, starting in 2002, he made the spy thriller grittier and more physical, and the role turned the Harvard writer into a credible action lead. Later came The Martian, where he spent much of the film alone on screen, talking to a camera.

Aquarius is rising in his chart, the sign astrologers associate with causes, fairness and a slightly detached, everyman ease. It fits the side of his life that has little to do with movies. In 2009 he co-founded Water.org with the engineer Gary White, a nonprofit focused on getting safe water and sanitation to people who lack them, and he has kept speaking for it ever since.

His Moon is in Capricorn in the twelfth house, a reserved, private placement in the most hidden corner of the chart. Capricorn Moons tend to steady themselves through work and responsibility rather than display, and the twelfth house keeps that emotional life out of view. Damon has long kept his family out of the spotlight; he married Luciana Barroso in 2005, and their life together rarely becomes part of the publicity cycle.

Mars in Virgo in the seventh house adds a practical, detail-minded edge to his partnerships. Virgo Mars does not grandstand. It prepares, revises and gets the work right, a decent summary of an actor who has spent three decades moving between blockbusters and smaller films without much drama of his own.

Astrology can describe a temperament but not a career. Still, a Libra in the house of shared ventures, steadied by a private Capricorn Moon, is a fitting chart for a man whose biggest win came from a school assignment written with his best friend.