The age they have come up with differs from previous estimates, and this suggests that the established technique of determining the ages of star clusters is much less reliable than astronomers had thought. (newscientist.com)
A group of methods for determining the age of objects, in years. (becominghuman.org)
If one makes an error of only 5 % in determining the age of an ice layer, for 40,000 - year - old ice that's an error of 2,000 years. (realclimate.org)