[ExI] New Hubble Deep Field Photos

BillK pharos at gmail.com
Mon Aug 20 18:16:13 UTC 2018

On 20 August 2018 at 17:14,  spike wrote:
>>... square of area about 100 arc minutes would be 10 arc minutes on a side.
>> The moon (and sun) are about 30 arc minutes across, so it is an area about a tenth of a full moon.
> We can make this work with only some minor brute force: a person can have a really really short arm
> (the T-Rex did) and imagine a really super huge grain of sand.  Sand is mostly quartz, and those can
> grow to arbitrary size methinks.  So just get a person with a short enough arm and a big enough grain
> of sand, and there you go.

Hmmmm...  Another way of looking at it is that the width of a thumb
(presumably a male thumb) :) held at arms length is about 2 arc
degrees = 120 arc minutes. So a thumb at arms length would block out
the moon. My thumb is about 1 inch wide, so a square of c. 1/12 inch
(c.2 mm) sides would be quite small. That's quite a big grain of sand,
though some types of sand are rougher than others.
The next size up is gravel, and it is definitely smaller than that. :)
See: <https://en.wikipedia.org/wiki/Sand>


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