Cygnus black hole confirmed by Harvard-Smithsonian Center for Astrophysics

Astronomers at the Harvard-Smithsonian Center for Astrophysics confirm the presence of a black hole in the constellation Cygnus.

The idea that objects exist whose gravity is so powerful that light cannot escape them has been around for centuries. But it was not until instruments aboard a rocket detected x-rays from an unseen source in the constellation Cygnus in 1964 that researchers considered the possibility that they had in fact discovered a black hole, an object from which nothing, including light, can escape. Seven years later, astronomers discovered a star in Cygnus orbiting something that could not be seen. “The dark object’s gravity seemed to be tearing gas from its bright companion,” says author and astronomer Ken Croswell, Ph.D. ’90, “and as the gas took the final plunge [see illustration], it became so hot it emitted x-rays.” But not everyone believed a black hole was the cause; in 1974, Stephen Hawking even bet another physicist that it wasn’t. Now the controversy (which Hawking conceded long ago, based on indirect measurements) has been definitively put to rest by Mark Reid and colleagues at the Harvard-Smithsonian Center for Astrophysics, who were able to calculate an accurate distance to Cygnus X-1, making possible an inference of its mass. Furthermore, they calculated that the gas closest to the dark object orbits it almost 670 times per second—a phenomenal rate that is half the speed of light—clear evidence of an object whose gravitational pull is so strong that it could only be a black hole. 

Read more articles by Jonathan Shaw

You might also like

In Sermon, Garber Urges Harvard Community to ‘Defend and Protect’ Institutions

Harvard’s president uses traditional Memorial Church address to encourage divergent views.

A New Narrative of Civil Rights

Political philosopher Brandon Terry’s vision of racial progress

This Astronomer is Sounding a Warning on 'Space Junk'

As debris accumulates in low Earth orbit, the danger of destructive collisions continues to rise.

Most popular

How MAGA Went Mainstream at Harvard

Trump, TikTok, and the pandemic are reshaping Gen Z politics.

Free Speech, the Bomb—and Donald Trump

A Harvard cardiologist on the unlikely alliances that shaped a global movement to prevent nuclear war

Explore More From Current Issue

Catherine Zipf smiling, wearing striped shirt and dark sweater outdoors.

Preserving the History of Jim Crow Era Safe Havens

Architectural historian Catherine Zipf is building a database of Green Book sites.  

Johnston Gate

Your Views on Harvard’s Standoff, Antisemitism, and More

Readers comment on the controversial July-August cover, authoritarianism, and scientific research.

People sit in lawn chairs near a rustic barn at Cider Garden in New Salem on a sunny day.

CiderDays Festival Celebrates All Things Apple

Visiting small-batch cideries and orchards in Massachusetts