A black hole is an astronomical object with gravity so strong that nothing—not even light—can escape once it passes its event horizon, the boundary around the singularity.
Stellar black holes form when massive stars (∼20× the Sun’s mass) exhaust their nuclear fuel, undergo supernova explosions, and collapse under gravity into a point with extreme density and curvature of spacetime. If the remnant core exceeds roughly three solar masses, no known force can resist the collapse.
Supermassive black holes—millions to billions of solar masses—reside at the centers of most galaxies, including the Milky Way. Evidence comes from tracking orbital motion of stars in their vicinity, as observed by NASA and ESA facilities, evidence that earned the 2020 Nobel Prize.
Black holes are invisible, but their presence is inferred from accretion disks—hot gas swirling around them emits powerful X-rays—and from gravitational lensing, where their mass bends light from background objects.
Observations by the Event Horizon Telescope (EHT) produced direct images of the shadow of black holes in M87 and Sagittarius A*, confirming Einstein’s predictions about light structure near the event horizon.
Some black holes move at high speeds through space, likely receiving small velocity boosts (often called kicks) from asymmetric supernova explosions or galactic interactions, as detected using Hubble’s precision astrometry.
Black holes also play key roles in cosmic evolution. Tidal disruption events—where a passing star is torn apart—produce luminous flares captured by Hubble and Chandra, providing rare glimpses into black hole activity.
Their immense gravity powers active galactic nuclei and relativistic jets, influencing both their surrounding galaxies and intergalactic environments.
22 January 2018
What if you could look out from the center of our Galaxy -- what might you see? Two scientifically-determined possibilities are shown in the featured video, an immersive 360-degree view which allows you to look around in every direction. The pictured computer simulation is based on infrared data from ESO's Very Large Telescope in Chile and X-ray data from NASA's orbiting Chandra X-ray Observatory. As the video starts, you quickly approach Sgr A*, the supermassive black hole in the Galactic center. Then looking out, this 500-year time-lapse simulation shows glowing gas and many points of light orbiting all around you. Many of these points are young Wolf-Rayet stars that have visible hot winds blowing out into surrounding nebulas. Clouds approaching close become elongated, while objects approaching too close fall in. Toward the video's end the simulation repeats, but this time with the dynamic region surrounding Sgr A* expelling hot gas that pushes back against approaching material.