"For example, sulfur is commonly known to have a standard atomic weight of 32.065. However, its actual atomic weight can be anywhere between 32.059 and 32.076, depending on where the element is found."
The origional article can be found here.
Humanity has the stars in its future, and that future is too important to be lost under the burden of juvenile folly and ignorant superstition. - Isaac Asimov