For now, but a few cascading collisions away and literally every dollar that's currently related to space stuff is at risk without cleanup.

This mission is just about de-orbiting debris, not trying to capture materials for reuse...

Makes complete sense and imagine that ancient night sky without any pollution.

That's one answer, especially if the final usage is downwell. If it's for orbital or luna construction, you never deorbit to Terra. You thinking parachute/water? I'd rather keep in orbit and start building a space elevator. :-) or a polar shield/mirror :-)

I don’t see how people would not notice about season changing and changes of the moon in the sky. And later, changes in time of sunrise, sunset, moon rise and moon set. I am betting on a few million years.

Don’t bother to look for documents of these “discoveries”.

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I boo this writer. That line "no exaggeration" is from a 2008 book on the history of astronomy across civilizations, and the first line of the preface is "It is no exaggeration to say..."

That suggests to me the writer of this article did not read the book at all. It is also odd that he would use this quote when every example in the article is far less than 5,000 years. If you look at his other articles, this is his thing. He cherrypicks quotes from books and inserts them as if it is wise and insightful. The topic is fine but idk this writer really bugs me.

Why can't you have two planets in each other's Lagrange points? That should be stable

Why not just… deorbit it? They’re not particularly resistant to atmospheric heating

This kind of boggles my mind cause I knew our moon was unusually large as far as such bodies go relative to their planets, but the fact it's only 2% while exerting 17ish% the gravity on its surface as we have on Earth seems counterintuitive. I know that proximity to the center of the mass influences how strong the gravitational attraction is, but damn, that's way more skewed than I had imagined.

Yeah it is absolutely possible, in terms of celestial mechanics.

In terms of the process of planet formation... it might be a bit improbable. But all that means is that you'd have to look for a while longer through the vast universe before you found it, right?

You could even paint a pretty clear picture by calculating the Earth-Earth Roche limit. Earth is not a rigid body, it is prone to deformation, but we could probably still use the rigid body equation if we give some extra padding. The Earth-Earth rigid body Roche limit is about 8000km so if you say it's ... I don't know... 2 or 3 times that you could probably avoid deforming your Earths too badly as they orbit each other.

In fact if you stick them at about 30 thousand km apart you could (I think...) preserve your 24 hour day, while also having a massive Earth in the sky of each Earth. But only from one part of each planet of course.

For people of this binary world, would be easier to establish a permanent presence in space than for us. But I think it would be harder to get to their Moon. (Assuming you keep our current Moon as it is, with maybe a slightly more wobbly orbit because of the proximity to the binary Earths around which it orbits.)

And of course exploring "the other Earth" would have been a major preoccupation throughout history. With all kinds of speculation and wild tales of what must lie above.

Really cool!

As a kid I had a glow in the dark picture of Earth on the bunk above me. I used to stare at the clouds on it each night as I went to sleep. I knew each and every twist in turn of the cloud pattern and I'm fairly sure I would notice a small change.

In the times before Reddit, tv, or even books I wouldn't imagine a great deal of time was spent staring at the night sky and that many people could have drawn star charts from memory.

It comes to me as no surprise that all throughout history humanity has had a very good concept of the motion of things in space

https://mars.nasa.gov/mars2020/mission/where-is-the-rover/

Zoomable map, here you can see the position of the rover, including the Sol dates of these collections.

More like twelve millennia. As Göbekli Tepe shows

https://astronomy.com/news/2020/09/gobekli-tepe-the-worlds-first-astronomical-observatory

You could have 2 planets in a relatively stable orbit for a very long time, like pluto and charon. However, fun fact, you cannot have 3.

I can certainly understand how... our fore-bearers saw the sky, the movements of the sun, moon, and stars and how animals and plants behaved ... breeding, growing, emerging, and hibernation ... how the timing of celestial events matched the seasonal behavior and used that information. Better yet, someone(s) was back there even thought of making star maps to help them remember over time. Clever apes with tools and then to the moon.

I think there is a good chance that either late stone age people knew about precession or it was discovered long before the official greek discovery of it

There is none without a customer to pay for the service and the only logical customer would be government or similar. We're in real need of some agreements that would actually fund useful cleanup operations, but probably a reasonably long way from getting them.

Some spicy lagrange'ing is about to happen

$29M would beg to differ on the lateness. Apparently a lot of new suckers can be born in 2 years.

U can say its already the state for the earth and the moon

You do that just fine from Earth. For a lot less money.

Imagine how sad it was for the people who had poor eyesight before glasses. Stars would be a blurry mess in the sky.

I think the "missing planet" is on the other side of the sun and we can't see it. Maybe.

Yes, I was going to cite that example too. Charon is fractionally largest "moon" (12%) tied to a "planet", so that could encourage tidal locking. (Earths Moon is second at 2%.)