Simply counting the number of rings will give one a fairly good idea of the age of the tree.Periods of heavy rain and lots of sunshine will make larger gaps of growth in the rings, while periods of drought might make it difficult to count individual rings. When a given quantity of an isotope is created (in a supernovae, for example), after the half-life has expired, 50% of the parent isotope will have decomposed into daughter isotopes.Trees undergo spurts in growth in the spring and summer months while becoming somewhat dormant in the fall and winter months.When a tree is cut down, these periods are exhibited in a cross section of the trunk in the form of rings.
There are well-known methods of finding the ages of some natural objects.
Using SAR imagery from Mini-RF on LRO, we have developed a method for dating small fresh lunar impact craters from the radar-bright halos around the craters.
These halos represent the ejecta lingering on the lunar surface and degrading over time.
The impactor is shattered into small pieces and may melt or vaporize.
Sometimes the force of the impact is great enough to melt some of the local rock.