In the early 1970s, renowned astrophysicist Jeremiah Ostriker from Princeton University found himself grappling with a troubling mystery that had arisen from telescope observations of distant galaxies. These mesmerizing cosmic discs appeared to be spinning wildly, yet they contained far too few stars and visible material to account for the gravitational forces holding them together. After much contemplation, Ostriker deduced that the answer lay in a far more substantial mass of unseen 'dark matter' that acted as a cosmic glue, preventing these galaxies from flying apart.

Although the notion of dark matter had circulated among scientists since the 1930s, it was Ostriker's groundbreaking work that played a pivotal role in persuading cosmologists to accept its pervasive existence throughout the universe. Today, the scientific consensus holds that dark matter constitutes a total cosmic mass six times greater than that of ordinary mattera ratio that closely aligns with what Ostriker and his research team at Princeton proposed in a seminal paper published in 1974. Despite these advancements, the true nature of dark matter remains an enigma, with astrophysicists still struggling to identify its components.

Jeremiah Ostriker, affectionately known as Jerry, was celebrated not only for his contributions to dark matter research but also for his wide-ranging inquiries across various astrophysical phenomena. As Martin Rees, Britain's Astronomer-Royal and a longtime friend and colleague, remarked, He was interested in all the new topics that arose, which later became integral to the scientific consensus. His inquisitive nature led to significant strides in understanding pulsarscelestial objects that emit radiationand the vast expanses of space between stars. He also made contributions to the roles of cosmic gas clouds in galaxy formation, as well as insights into the dynamics of supernova explosions.

Born in April 1937 to a Jewish family in New York City, Ostriker was the son of a public school teacher mother and a father who ran a clothing company. From a young age, his fascination with science was evident; at just 13 years old, he took the subway to a Broadway bookstore to purchase a copy of 'Teach Yourself Calculus.' This early passion set the stage for a remarkable academic journey.

Ostriker began his higher education at Harvard University, where he earned a degree in science. Interestingly, he found classes in art, history, and literature to be more intellectually stimulating than his science coursework. He later reflected in a memoir published in 2016 that a course he took with the poet Archibald MacLeish was among the best training he received for his scientific career. His time at Harvard also brought him personal joy as he married Alicia Suskin, an undergraduate at Brandeis University who would go on to become an acclaimed poet in her own right, adopting the name Alicia Ostriker.

Despite his challenges with the astronomy curriculum at Harvardso poor that he petitioned the dean to drop it after just one termOstriker's passion for astronomy was unwavering. He pursued a PhD and conducted postdoctoral research in astrophysics, eventually joining Princeton University as a lecturer in 1965. Princeton would become his academic home for life, although he also held a professorship at Cambridge University during his career.

In addition to his research, Ostriker stood out for his willingness to engage in university administration. He dedicated considerable effort to administrative roles, notably serving as the chair of his department and later as provost at Princeton. His leadership in astronomy was also evident in his role as a scientific leader and fundraiser for the Sloan Digital Sky Survey, which has been operational since 1998 from a dedicated telescope in New Mexico. This ambitious project has created the most comprehensive map of the visible universe, and Ostriker was adamant that the data should be freely accessible to astronomers around the globe. This commitment has resulted in over 10,700 research papers encompassing a wide range of discoveries.

As provost, he championed financial aid initiatives that have made Princeton more appealing to a diverse array of students. His colleagues praised these efforts in a testimonial, acknowledging the success of his initiatives in promoting inclusivity. In his 2016 memoir, Ostriker expressed his strong commitment to advancing diversity in the field of astronomy. He noted that when women began entering the field as full-fledged colleagues in the 1960s and 1970s, their contributions were immediate and transformative.

A particularly proud moment for Ostriker occurred in 2012, the same year he became a professor emeritus at Princeton, when his daughter Eve was appointed as a professor of astrophysics at the university. Reflecting on her journey, Eve remarked, Growing up, I dont think either my father or I had the expectation that I would go into the family business. What drew me to astrophysics in graduate school was the same allure that captured his attention 30 years earlierthe universe's ability to present us with problems that are, in principle, solvable. She added, What he loved most was diving into puzzling phenomena, brainstorming potential explanations, and meticulously working through each idea.