Re: Visualizing

On 9/7/24 19:16, Martin Brown wrote:

On 07/09/2024 17:07, john larkin wrote:
 

I suppose that being nearsighted has social-evolutionary advantages.
Some people shoot arrows, some people make arrows.

 Having extreme visual acuity was highly prized back in the days before there were optical aids. Roman centurions had an eye test for lookouts based on splitting the close double epsilon Lyra (which is at the limit 3' arc of the human eye). I could do it when I was younger.
 A very small number of children and young adults can see the Galilean moons of Jupiter at greatest extension from the planet (a feat that most people need a telescope or binoculars for hence Galileo's discovery). Seeing them against the planet's glare requires both good optical figure lens and very clear fluid gel in the eyeball.
 Splitting Alcor & Mizar in the plough is easy by comparison (anyone with 20/20 vision should be able to do that). Ancients used it that way too.
 https://en.wikipedia.org/wiki/Mizar_and_Alcor
 

I was surprised when my 3-year old son described venus as a 'little moon'. To my unaided eyes, it was just an unusually bright pinpoint.
Jeroen Belleman