AST201H1 Lecture Notes - Lecture 6: Event Horizon, Escape Velocity, Apollo 10

• School: UTSG
• Department: Astronomy & Astrophysics
• Course: AST201H1
• Professor: Macdonald

Document Summary

Escape speed: apollo 10 astronauts reached a maximum speed of 39,800 from earth"s surface is about 40,000 km/h (11 km/s) Inside event horizon, escape velocity is > speed of light, nothing can escape. Black holes are not cosmic vacuum cleaners: behave like you would expect them to due to gravity do not suck things into them. How to nd black hole today: we look for objects that appear to be orbiting an invisible object. 1973, astronomers discovered a star orbiting something small and dark which was 15 times the mass of the sun. Later observations showed that the small dark thing was much smaller. January 23, 2020: cygnus x-1: a black hole devouring its companion star. Remember: nothing escapes a black hole"s event horizon: cygnus x-1 is about 15 times the mass of the sun, which gives is a schwarzschild radius of. X-rays are observed originating from just outside the event horizon.