Andromeda Proof

Let's compare the angular diameter of Andromeda to that of the moon. If the picture is accurate then the angular diameter of Andromeda should be about 5-6 times what we get for the moon.

We'll use the formula s = 2 arctan(d/2D), where s is the angular diameter, d is the actual diameter of the object and D is the distance to the object.

Note that the units of d and D can be anything but they have to match.

Andromeda: From wikipedia d=141 kly and D = 2.54 Mly = 2,540 kly. Then from the formula s = 2 arctan(141/(2*2540)) = 0.055.

Moon: This time d = 3,474.8 km and D = 384,400 km. From the formula s = 2 arctan(3474.8/(2*384400)) = 0.00904.

The ratio of the two angular diameters is 0.055/0.00904 = 6.08, which is very close to the range that I estimated if the picture were correct.

Status: Confirmed.

~tornado28