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
We now use the caesium standard, where a second is defined by a fixed number of periods of a fancy atomic clock. We then use this second to define a minute, hour, day, and eventually year.
(more specifically, a second is defined by a constant number of transition period of caesium-133 hyperfine ground states)
So to answer your question, the age of something has nothing to do with how many times the earth rotates or orbits around the sun, but the number of ticks on a clock. A thing is 1 billion years old if it is created (1 billion x 365.24 x 86400) seconds ago.
Latest Answers