Anatomy of a Black Hole

Black holes are among the most enigmatic objects in the cosmos, extensively studied yet not completely understood. Contrary to their name, black holes are not actual holes but rather incredibly dense concentrations of matter compressed into very small regions. The gravity near their surface, known as the event horizon, is so powerful that nothing, not even light, can escape. Unlike Earth’s or the Sun’s surface, the event horizon isn’t a physical surface but a boundary enclosing all the matter of the black hole. While there’s still much to learn about black holes, such as the nature of matter within their event horizons, scientists have gathered significant knowledge about them. Black holes do not emit or reflect light, rendering them effectively invisible to telescopes. Researchers primarily study black holes through their impact on surrounding matter: Black holes can be encircled by rings of gas and dust, known as accretion disks, which emit light across various wavelengths, including X-rays. The intense gravity of a supermassive black hole can cause stars to orbit it in specific patterns. Observations of star orbits near the Milky Way's center provided evidence of a supermassive black hole, a discovery that earned the 2020 Nobel Prize. When massive objects accelerate through space, they produce ripples in space-time known as gravitational waves, detectable by their effects on specialized instruments. Massive objects like black holes can also bend and distort light from more distant sources, a phenomenon called gravitational lensing, which helps scientists detect otherwise invisible black holes.