[Request] Tattoo help
Feel free to delete this if this isn't quite what the sub reddit is for, but my friend wants a tattoo, and she wants my help.
The idea is to get a scale model of the earth and moon on the back of each of her hands. Now for the maths:
Average distance between earth and moon:
384,400,000 m
Radius of the earth: 6,378,000 m
Radius of the moon: 1,737,400 m
Distance between center of hands: 1.53 m
Do i just do:
(Distance between center of arms) / (Distance between E and M) to get the ratio of the scale. Then multiply the size of the earth and moon to get how big they would be at the scale she is looking for
(1.53 / 384,400,000) × 6,378,140 = 0.025 m or 2.53 cm
(1.53 / 384,400,000) x 1,737,400 = 0.0069m or 0.69 cm
So this ends up with an earth 2.53 cm wide on one hand and a moon 0.69 cm on the other hand with a distance between their centers being 1.53 m.