41–50 of 89 posts
All nations of the world must band together to build a harpoon, of immensity and grandness the likes of which has never seen before. The moon cannot be allowed to escape.
I feel sorry for our future colleagues software developers, that will have to deal with calendars, public holidays and all other stuff related to the lunar calendar. There are many religions that use the lunar cycles as basis for their calculations: https://en.wikipedia.org/wiki/Lunar_calendar
Earlier quoted context omitted.
This can't be true: you can choose a point behind any sufficiently round satellite where it appears the same size as the star. Perhaps it's the only place we know of on a planet's rocky surface. But most of our solar system's planets with moons don't have rocky surfaces, and we can't detect moons in other systems, so you really mean it's not true from the surface of Mars, Pluto or Charon. Additionally, the moon varie…
Yes, sorry, I should have also wrote "where one can stand".
Earlier quoted context omitted.
The surface of the Earth is the only place we know of where a natural satellite appears exactly the same size as the primary / only star.
This can't be true: you can choose a point behind any sufficiently round satellite where it appears the same size as the star. Perhaps it's the only place we know of on a planet's rocky surface. But most of our solar system's planets with moons don't have rocky surfaces, and we can't detect moons in other systems, so you really mean it's not true from the surface of Mars, Pluto or Charon. Additionally, the moon varie…
David Kipping's Cool Worlds lab at Columbia has done some promising research on this, some of which is detailed in excellent videos on their youtube channel.
> We found that the moon was around 60,000 kilometers closer to the Earth then [2.46 billion years ago] (that distance is about 1.5 times the circumference of Earth). This would make the length of a day much shorter than it is now, at roughly 17 hours rather than the current 24 hours. I wish they explained why the moon being that much closer would have such a dramatic effect on the day length. Can someone explain thi…
Earth-Moon momentum is conserved.
Think of a pregnant woman (the Earth) spinning on a seivel chair. The woman gives birth to her child (the Moon) and she takes the child in her arms and extends it at arm's length.
Their rotation slows down, just like an iceskater slows down when spinning and extending their arms.
The Earth does not have phisical arms holding the Moon, but it has gravity and the Moon also has gravity that affects the ocean tides -- the tidal effects are like tiny tiny arms that both the Earth and the Moon use to push eachother away (and lose a lot of energy in the process also).
The Earth is losing rotational momentum at the expense of the Moon, which is gaining momentum and increasing speed in traveling around the Earth which increases the centrifugal force which means the Moon goes to a higher and higher orbit and further and further away from Earth.
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If the moon's orbit is increasing in radius, doesn't that mean its orbital velocity is decreasing? Which way is energy being transferred? This stuff confuses me.
Its relative velocity with respect to a Cartesian frame of reference fixed on the surface of the Earth may be dropping, but that's not particularly meaningful. Think of the moon being in free fall, without any external forces acting on it. It would be moving at a constant velocity in a straight line, except the space and time it is in is curved due to gravity. Because of that curved spacetime, the moon appears to acc…
I feel sorry for our future colleagues software developers, that will have to deal with calendars, public holidays and all other stuff related to the lunar calendar. There are many religions that use the lunar cycles as basis for their calculations: https://en.wikipedia.org/wiki/Lunar_calendar
Lunar calendar? How about the rotation of the earth? I imagine the further out it gets, the further out our moment of inertia, the slower the earth spins. Days get longer, but the length of a year stays the same. That'll be a fun one. We would probably have day length deniers/365 purists who believe nothing is changing for centuries.
> We found that the moon was around 60,000 kilometers closer to the Earth then [2.46 billion years ago] (that distance is about 1.5 times the circumference of Earth). This would make the length of a day much shorter than it is now, at roughly 17 hours rather than the current 24 hours. I wish they explained why the moon being that much closer would have such a dramatic effect on the day length. Can someone explain thi…
> wish they explained why the moon being that much closer would have such a dramatic effect on the day length. Can someone explain this? Seems off to me, but I'm very physics-naive Earth-Moon momentum is conserved. Think of a pregnant woman (the Earth) spinning on a seivel chair. The woman gives birth to her child (the Moon) and she takes the child in her arms and extends it at arm's length. Their rotation slows down…
Just in case any of you were thinking of patenting this idea, I'm afraid that someone beat you to it: https://patents.google.com/patent/US3216423A/en