Light years?

Question

the spiral galaxy in the andromeda constellation is aboout 2*10^19 km away from us. how many light years is this?

how to calculate light years? thanks very much~

Answer 1

2x10^19km = 2.11x10^6 ly

1ly = 9460730472580.8km

therefore, in order to convert you would do:

2x10^19km * (1ly / 9460730472580.8km) = 2,114,001.669ly

Answer 2

1 ly = 3 x 10^8 m/s x 3600 s/h x 24 h/day x 365.24 day/y = 9.467 x 10^15 m = 9.467 x 10^12 km

So the spiral galaxy in the Andromeda *nebula* is 2.11 x 10^6 ly away.