Answer:
[tex]2.537\times 10^{6}\ years[/tex]
Explanation:
Distance to Andromeda galaxy
[tex]2.537\times 10^{6}\ ly=2.537\times 10^{6}\times c\times y[/tex]
Speed of light is
[tex]c=3\times 10^8[/tex]
Time is given by
[tex]t=\dfrac{Distance}{Speed}\\\Rightarrow t=\dfrac{2.537\times 10^{6}\times c\times y}{c}\\\Rightarrow t=2.537\times 10^{6}\ y[/tex]
Hence, the light from Andromeda left [tex]2.537\times 10^{6}\ years[/tex] ago
