So, if we say something is 1 billion years old, is that (365 spins on earth’s axis x 1 billion)? Is it (1 trip around the sun x 1 billion), or a different measurement? The answers to those change depending on how it’s calculated.
In other words, if I say I lived one year, that means 24 hr/day for 365 days/year in todays terms. Over time the earth’s orbit of the sun becomes faster and slower changing the meaning of a year. Also, as the earth spins faster and slower on its axis, a day in terms of hours is different relative to today. It breaks my brain.
What about the needs for adjustments for leap years? How does this influence radiometric dating? If a molecule degrades by 1 measurement every 300,000 years, the first 150,000 years are going to be different than the last half. If you want to pinpoint the halfway mark, where is it?
In: Planetary Science
Generally, we use years as a time unit for simplicity and ease of communication. It is assumed to be a trip around the sun, about 365.25 days (365.2422 if you need precision). When we are talking about things that happened 200 millions years ago it is an approximation. Other time units are more suited for large periods of time like: era, eon, epoch, age…
For dating, any scientific methods will use the second as the standard unit of time. It is then converted to years to be more readable by dividing by 60x60x24x365.2422 or a similar conversion.
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