What did you use to measure?
All golf balls are the same diameter: 1.685".
Keep in mind that as the diameter of a sphere increases its volume
increases exponentially... a 2" diam. onion will contain better than
three times the volume of a 1" diam. onion. For most cooking it makes
more sense to weigh a diced onion than to eyeball its size or to use a
measuring cup. That's why onions are sold by weight. Most times for
soups/stews I peel onions but leave them whole, this cook's treat.
Onions being an allium, same as daffodils, they are somewhat toxic to
mammals, which is why deer won't eat onions, garlic and daffodils.
onions make my wife sick, so that I braise them whole as a compromise,
they impart flavor but very little of the toxin. However most times I
leave the onions out, or I'll include one whole onion to a large pot
of soup and fish it out early. I like braised onions, onions don't
affect me, I can eat lots of raw onion with no ill affect but I eat
them when my wife isn't home, the smell of onion makes her ill... yet
she can eat lots of garlic cooked in a sauce.