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Comment by neltnerb | Hacker News Reader

"their resolution is so high that you could see a golf ball from about 15 miles away."

Okay, that's just a nerd swipe. What's the field of view! Oh journalism...

Edit: Below is incorrect. They claim the total area is enough to capture 40 full moons, not that the sensor is 40 full moons across. Assuming a perfectly round sensor you could estimate its radius from that, but that's too much on my phone.

Maybe they "left it as an exercise for the reader"? ;-)

The FOV is "40 full moons", so 40•0.5° = 20°. For a plane 15 miles away that comes to an image covering 2•15•tan(10°) miles = 5.3 miles.

So you can spot a golfball on an image that's 5.3 miles large.

Assuming the sensor is 7 full moons across as indicated in their figure, the FOV is only 3.5°. In this case the plane at 15 miles distance is only 0.9 miles across.

On one of their picture, it shows 7 moons wide, which is probably a good approximation (6 lines of those 7 moon images does seem close to filling the area of the sensor in their pictured representation, if you then shift some moons when the sensor lines get shorter at the top and bottom).

So using your calculation it could be, approximately: 7*0.5° = 3.5° in FOV.

Doesn't it say right above that it's 7 moons wide? A moon is 0.5 degrees, so that makes it 3.5 degrees.

I would not assume that it had the same optics when they are describing the CCD. That is all.

It is just a darn weird thing to say when they could have just used a more standard analogy for contextualizing resolution.

The field of view is also on TFA: ~ 40 lunar circles

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