Yes, but she’s still “showing” it to us.
If the sun lasted long enough, we would expect the earth to tidally lock to the moon, completing one rotation every 30 days or so. The moon will have moved further away during this time, its orbital speed having increased due to the tidal locking process.
Again assuming the sun lasts long enough, we’d also expect the earth to tidally lock to the sun in the same way that the moon is currently tidally locked to the earth. This should slow the moon down, and eventually we’d expect it to spiral down below the Roche limit and break up. It’s gonna be pretty.
Venus constantly showing us her backside is either rude or naughty.
Eh? Venus is the only feminine planet. Mercury, Mars, Jupiter, Saturn, Uranus, and Neptune are all named after male gods. Planets don’t usually get a gendered pronoun, but on the rare occasions that they do the pronoun tends to follow the gender of the god/goddess that the planet was named after.
Ships are female because of tradition. There seems to be some debate on exactly how this came about. The older languages that mixed together and evolved into English were gendered, and most of English’s closer relatives (French, Spanish, German) all use gendered nouns. You could turn the question around and ask why most things in English aren’t a he or a she when English has its origins in gendered nouns.
As for ships being female instead of male in gendered languages, one common explanation is that ships were guided by mothers or goddesses when sailors would pray for safe voyages. But as I said, this seems to be a bit debatable as different sources will give different reasons. Other reasons given are that Mother Nature is female so sailors gave ships female names to appease her, or that ships are only female because the Latin word for ship (navis) is female.
Ironically, even though ships are female, for most of history it was considered bad luck to have a woman on a ship.
Ships are neuter in German (and Old English), so, to the extent it has a gender in English, it should be neuter. Unless that changed somewhere along the line? Beyond that it’s like Private Pyle calling his M14 “Charlene”. (Rifles can be feminine in e.g. Russian, though, depending on the word used.)
I had to poke around on Google a bit for this. Apparently by the 1300s it was common to refer to ships as “she”, but while we know that the change happened sometime before then, nobody seems to know exactly when or why it changed.
All true, but there are other astronomical bodies named after females. For example, by tradition, the moons of Jupiter are named after Zeus’ lovers, except for Amalthea, who is his foster mother. Those are predominately female, with the notable exception of Ganymede. So Io, Europa, Callisto, Himalia, Leda and others are female. However, there are somewhere around 80 known satellites of Jupiter and many are not yet named. I’d be surprised if there are that many lovers of Zeus in Greek mythology, so at some point they’ll have to find another source of names.
Another tradition of female names in astronomy is asteroids. The early ones (Ceres, Pallas, Juno, Vesta, etc) were named after goddesses, although they’ve long since dropped that tradition. But they hadn’t totally exhausted the names of the goddesses before moving on to other names. Mike Brown found that none had been named for Eris when he wanted a name for a large TNO he’d discovered in 2005.
But I can’t recall any use of a female pronoun for these bodies. That doesn’t mean no one has ever used one, but if so, it’s extremely rare.
You have that backwards, though. A lower orbit is faster, a higher orbit slower. The raw math puts the day/month sync rate at about 1128 hours (47 today days). It seems to me that this position would move the barycenter inward (it is now on the order of two thousand miles from Earth’s center) due to lower gravitational effect from the moon, so I think the tidal locking might be a transitory state (“transitory” meaning “only” a few million years), as I fail to see a reason that the moon would cease to recede.
The Moon’s recession is caused by tidal drag. Tidal drag results from a difference in the rotation period of the planet versus the revolution period of the satellite. Once these two periods are the same, there’s no more drag and the recession stops.
I thought it was the tidal bulge of the oceans lagging behind a bit which dragged on the moon. I may be misremembering or misinformed.
You’re remembering it right. The lagging is in how quickly the tides relax after passing the sub-lunar point. You only get that lagging when the rotation/revolution periods are different. “Tidal drag” is just shorthand for that phenomenon.
Although a nitpick. The tidal bulge is not just in the oceans but also in the land. The oceans bulge more, because they’re more fluid, but the land gets tidal bulges too. IIRC, the land only bulges something like a foot or so. You don’t notice because it all moves together, just like you wouldn’t notice tides in the middle of the ocean.
Really?
That feels not right (and I know the universe does not operate according to my feels).
But some things will not stretch…like granite or the Empire State Building. Other things are more flexible…like dirt.
I would think picking up the Empire State Building and dropping it a foot each day would lead to trouble. Even if you said all of Manhattan was being picked up there must be a place where some things give more than others…e.g. where a hunk of granite meets dirt. I cannot imagine pulling a foot a day across the US (or world really) wouldn’t have more noticeable effects. I’d think the friction alone would make things pretty hot.
The above is me mostly thinking out loud. I do not pretend to know how it is all working. Just seems crazy (my way of saying I am really asking how it works).
Over scales the size of a planet, everything is a fluid. Granite stretches. It stretches only a very tiny amount, but one foot over a whole planet is, indeed, a very tiny amount.
As for ships, I suspect that they’re female just because sailors are male and mostly heterosexual.
Now that’s desperate.
I wasn’t going to do the math, but you’re right, when the earth tidally locks to the moon, the moon’s orbital period will be quite a bit longer than the current 29.5 days; I’ll trust that you did the math right and it ends up at about 47 today-days, with the moon in a considerably higher orbit than it is now.
But the second part still holds: given enough time, eventually the earth will tidally lock to the sun - and tidal drag will slowly decelerate the moon’s orbital velocity, making it drop lower and lower.
OK, here is what I see happening: In about 3Gyh (billion years hence), the sun has become so hot that Earth has lost its volatiles, significantly reducing the major tidal effects. The moon’s outward migration has consequently slowed somewhat, and at its distance, the barycenter has moved inward, reducing tidal drag on the Earth. About 6Gyh, the sun goes off main sequence and starts to expand (this may happen later than the raw models suggest, due to tidal effects within the sun itself, caused by big Old Jove).
At this point, the terran system will be immersed in the solar atomsphere, and while it will be comparatively tenuous, two things will happen: the Earth and moon will accumuate mass from the atmosphere, increasing the Earth’s spin marginally; and they will experience some amount of aerodynamic drag.
The effect of that drag will gradually push the Earth/moon system into a higher orbit, but, more importantly, the moon will experience more drag on its inward pass than on its outward pass, so the Earth will start to fling it into a more elliptical orbit. If that continues long enough (probably not – less than 1Gy), the moon could end up settling into Earth’s L4, in which case the Earth and the moon could both end up tidally locked to the sun, some 2~3Tyh.
In any case, a body that slows in its orbit moves outward, but as long as the moon orbits the Earth, that is what inhibits solar tidal locking. If the sun exerts measurable tidal drag on the earth, that would cause the moon’s orbit to expand, not contract, either causing it to eventually settle at L5 or L4 or to be sent on a different trajectory by passing too close to Venus.
Meanwhile, by some 7~8Gyh, the sun has cast off half its mass and shrunk into a white dwarf, so the overall dynamics of the ex-solar system have changed beyond recognition. The Glurpflorgles from Pnledfarb will pass through the wreckage and have no clue that there was ever anything here worth looking at, or might construct outlandish theories about what might have been here just a few Gya.
As the Moon moves out, the Earth-Moon barycenter will move out too. The Moon’s outward movement will slow because the tides will become smaller and hence tidal drag will be reduced.
I’ve seen several projections on this. Some say it will be immersed, some that it’ll just barely escape. I think the problem is exactly how much mass the Sun will lose as it ages. The more it loses, the more Earth’s and the other planets’ orbits will move outward. But there’s probably some uncertainties involved, such as exactly how much the Solar wind will increase as the Sun gets hotter.
Most non-Keplerian effects, including drag, tend to circularize orbits, not eccentrize them.
Can you explain the mechanics of how this would happen? ISTM this would require the solar atmosphere that is farther from the sun to be orbiting the sun faster than the solar atmosphere that is closer to the sun. Do we know this would be the case?
This would require the solar atmosphere in the path of the earth to be orbiting the sun faster than the earth is orbiting the sun. Do we know this would be the case?
I’m pretty sure this is incorrect. While it’s true that orbital velocity in higher orbits is greater than in lower orbits (LEO, a few hundred miles above the surface, ~17,400 MPH; geosynchronous, about 22,000 miles above the surface, ~7,000 MPH), it doesn’t follow that applying a decelerative force causes a satellite to move to a higher orbit. When we want to deorbit a spacecraft, we slow it, and it drops into a lower orbit (or at least an elliptical orbit with minor axis smaller than its previously round orbit) that intersects the atmosphere.
The inverse appears to be true, i.e. a body that moves outward in its orbit (due to an externally applied force, e.g. a rocket engine or a tidal pull) tends to slow its orbital velocity. That’s pretty much what’s happening to the moon right now.
It’s true that the moon orbiting the earth inhibits solar tidal locking of the earth, but it doesn’t absolutely prevent it; it’s just one more source of energy that makes solar tidal locking take longer than it otherwise would. If the sun exerts tidal drag on the earth (and it surely does), it will tend to cause the earth’s spin to slow, just as the earth has caused the moon’s spin to slow to 1 revolution per orbit. As its spin slows,