•Q1. We see the Crab Nebula is about 1.35 parsecs in radius and is expanding at a rate of 1400 km/s. Extrapolate backwards in time and estimate about when would the supernova creating the Crab Nebula have exploded?
–Distance/rate/time problem
so…
•1.35 pc = 1400 km/s x
time
•Convert pc to km: 1pc =
3.09 x 1013 km
•Time = (4.2x1013km)/(1400
km/s) = 3 x 1010 s
•Convert to years: 31.5
million seconds in a year
•Time = 950 years (if you
don’t round get 920)