VERDICT: TRUE The viral TikTok claim that the first black hole ever discovered is Cygnus X-1 is accurate. **Claim-linked findings:** 1. **Cygnus X-1 was the first cosmic object identified as a black hole.** NASA's official article on the IXPE mission states: "Cygnus X-1, discovered in 1964, was the first cosmic object ever identified as containing a black hole." NASA's "Imagine the Universe!" educational page likewise confirms: "Cyg X-1 has the distinction of being the first object identified as a black hole." 2. **The discovery timeline is consistent.** The X-ray source was first detected in 1964 during a sounding-rocket flight, and it was established as a black hole in the early 1970s through the work of Bolton (1972) and Webster & Murdin (1972). The peer-reviewed review paper "Fifty Years After the Discovery of the First Stellar-Mass Black Hole: A Review of Cyg X-1" (Jiang, 2024) confirms: "It was the first system widely believed to host a stellar-mass black hole (BH) after the work of Bolton (1972); Webster and Murdin (1972). The discovery of Cyg X-1 as an X-ray source dates back even further, to 1964." **Source URLs (two independent primary sources — U.S. government and peer-reviewed journal):** - https://www.nasa.gov/universe/nasas-ixpe-reveals-shape-orientation-of-hot-matter-around-black-hole/ - https://imagine.gsfc.nasa.gov/features/yba/CygX1_mass/cygX1_more.html - https://arxiv.org/html/2411.12507v1 (peer-reviewed review, published in the journal Galaxies) Note: A minor nuance — the black hole was *identified/confirmed* as such in the early 1970s, though the X-ray source itself was *detected* in 1964. The claim's core assertion that Cygnus X-1 is the first black hole ever discovered is correct.