David Kipping

you can find inspiration and intellectual joy in just the smallest little thing that starts a whole thread of building upon it and wondering about the implications.

And so in this case, I was just really struck by, we kind of mentioned this a little bit earlier, the idea that stars are not static.

We tend to think of the galaxy as,

as having stars in a certain location from the center of the galaxy, and they kind of live there.

But in truth, the stars are not only orbiting around the center of the galaxy, but those orbits are themselves changing over time.

They're processing.

And so in fact, the orbits look more like a spirograph, if you've ever done those as a kid.

They kind of whirl around and trace out all sorts of strange patterns.

And so the stars intersect with one another.

And so the current closest star to us is Proxima Centauri.

which is about 4.2 light years away, but it will not always be the closest star.

And over millions of years, it will be supplanted by other stars.

In fact, stars that will come even closer than Proxima within just a couple of light years.

And that's been happening, not just we can project that will happen over the next few million years, but that's been happening presumably throughout the entire history of the galaxy for billions of years.

And so if you went back in time, there would have been all sorts of different nearest stars throughout different stages of the Earth's history.

And those stars are so close that their Oort clouds do intermix with one another.

So the Oort cloud can extend out to even a light year or two around the Earth.

There's some debate about exactly where it ends.

It probably doesn't really have a definitive end, but kind of more just kind of peters out more and more and more.

as you go further away by the way for people who don't know nor cloud i don't know what the technical definition is but a bunch of rocks that kind of no objects that uh orbit the the the star and they can extend really really great because these are objects that probably are mostly icy rich um they were probably formed fairly similar distances to jupiter and saturn but were scattered out through the interactions of those giant planets um