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
The half-life of uranium doesn’t care how long a day is. All that matters is the strict passage of time. For example, we measure the age of the Earth as a little bit over 4.5 billion years, **as we currently measure years**. Even if Earth’s orbit was different way back then and it went around the sun more quickly or more slowly, that doesn’t change its absolute age.
And, with leap years being an artefact of the calendar we use, scientists go for a more… well… scientific approach. Officially, the length of the year is 365.26 days. So that’s what scientists use. They’re not going to try to calculate exactly what point in the Julian calendar something occurred in.
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