1. The problem statement, all variables and given/known data Hi. The Crab Nebula which can be seen with even a small telescope, is the result of a supernova. All parts of the nebula are moving away from the centre at 1.18*10^6 m/s. The angle that the Crab Nebula forms with the Earth is 0.083 degrees. This supernova was observed by chinese astronomers in 1054. You can assume that the Crab Nebula has expanded at a uniform rate since then. - What is the distance from Earth to Crab Nebula? 2. Relevant equations Distance = Speed of light * Time elapsed. 3. The attempt at a solution I said that there was 2014-1054=960 years since we first observed it. Hence 960 lightyears which is equal to 9.1*10^18 m. However, this is wrong according to the answers (and wikipedia while we're at it). Btw, what do I need the expansion speed for? It's so small compared to c. And what about the angle? Any help is appreciated. Thank you.