I love astronomy stuff, not an expert at all, but have always been so fascinated by it. I am totally baffled by how we seem to claim that we can approximate how long the sun has been around. Like the margin of error for a number like that is crazy…. totally incomprehensible to me. Say that we are 25% off, that means we are over 1 billion years off. So, how do people confidently claim that the sun is 4.6 billion years, rather than 3 billion or 10 billion?
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The sun is what’s is called a “main sequence star.” Stars like the sun follow a predictable lifecycle of forming, burning, changing characteristics over their lives, and then dying one of several different ways.
We know this fairly accurately through a combination of observations and calculations.
We can easily plot the sun on a table of measured size, mass, luminosity, composition, and other factors to get us a good idea of its age.
Also, the fact that all the planets formed at the same time as the sun and we can also measure *that* helps us get a good picture of when it was formed.
Highly recommend the [Bedrock: Earth’s Earliest History](https://podcasts.apple.com/ca/podcast/bedrock-earths-earliest-history/id1608064632) podcast. Episode 3 explains the science behind the dating game.
We counted the candles on the cake?
This fact is a doozy for ELI5. It’s built on a large number of astronomical observations, combined with an understanding of gravity, thermodynamics, and atomic and nuclear processes, which in turn were developed by terrestrial physics experiments. Though hypotheses about solar formation pre-date quantum mechanics, its advent in the early 20th century was pivotal in understanding the composition and life cycle of stars, thus allowing a determination of a precise age. A satisfactory answer in my opinion would require much more background, and could easily take up an entire semester of university-level survey course.
Check out the movie Oppenheimer. The movie is less about the actual science, and is primarily a story about a thoughtful and talented man who gains influence because he is instrumental to power, and is ultimately discarded once he’s served his purpose. But there is a backdrop of nuclear physics discoveries taking place in the context of stellar processes. That’s what people like Oppenheimer and Teller were trying to understand, and the knowledge just happened to have other applications (ie the bomb).
Here is a Youtube series that I love that is very accessible. David Butler goes through the math and the theory of how the Universe, Stars, Earth, and Solar System ages were determined in a way that any high schooler could understand. It’s thorough without being overly complicated or patronizing. I will warn you that his voice is very relaxing.
Was the [faint young sun paradox](https://en.wikipedia.org/wiki/Faint_young_Sun_paradox) ever resolved?
I think you are getting at multiple different questions here.
* What is the age of the sun?
* How do we know?
* What is our margin of error?
* How do people confidently claim a precise number with such a huge margin of error?
Each one of the questions is difficult to give a good eli5, but the philosophical questions about “how do we know what we know, and who do we trust?” are at the center of science.
We have put systems in place to help us know who to trust, and when, and to help find error.
we know how large the gas tank is and we know how much gas is left. we also know the rate of fuel being burnt. doing the math we can figure out how much of the gas has been used and so know how long the fuel in the tank has been burning. we also know how long the tank will last until we run out of gas.
unfortunately the universe is so big that we may not reach a refueling station in time before we run out. its like a tesla and a charging station.
I’m curious about something and too lazy to research it. We talk about sending a manned mission to Mars but what about Venus?
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