this post was submitted on 01 Apr 2025
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Futurology
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(didn't read the article, yet)
Would be neat if this was the mysterious planet 9 and it was flung out of the solar system by Jupiter during the formation of the solar system. Could a planet realistically travel 47ly away in the time since the solar system formed? ๐ค
Google says solar system formed 4.6 billion years ago, but I'm gonna say 4.7 billion bc that would mean the planet would need to travel one light year every 100 million years.
And it would not need to go fast to do that - about running speed according to wolfram alpha
So there's definitely a chance! Which I wouldn't have expected.
Per reddit, our probes take about 16,000 years to go one light year.
It's unlikely that a random system would orchestrate a gravity assist as well as we can, but even at 1,000x slower than us, that'd put the planet leaving the solar system <1 billion years ago (~750 million years ago).
If I recall, the earth is 4.5 billion years old?
So if that planet was traveling at about 1/billionth the speed of light, it could be nearly 47 light years away now.
I think that's roughly 1000km/h which sounds perfectly achievable considering we orbit the sun at 67,000km/h.
4.5 billion divided by 1 billion is 4.5. You're off by an order of magnitude.
Also, there is a lot of stuff we can see within 47 light years. Stumbling across a planet that was ejected from our solar system is highly improbable, but even less so is that planet being captured by another star and having a stable orbit. Not impossible, mind you, but the lottery is a safer bet.