The gas shell of a planetary nebula is expanding (away from the central star) at 20 km/s. The nebula currently has a diameter of 1 light year. What is the age of the planetary nebula(time since the gas was ejected)?
This problem uses the basic formula relating velocity, distance and time
v = d / t or, for this problem, t = d / v.
What is moving in this problem is the outer layers of the ...
This solution computes the age of the nebula.