zephyr

There are many many many examples of what some might consider "personal freedoms" which are curtailed and regulated by local, state, and federal laws. Most people don't make a stink about it because it's common place and baked into the system and it's all they know. See, e.g., "No Shirt, No Shoes, No Service" (which is a limit people readily accept) vs "No Mask, No Admittance" (which many people actively fight).

@AzorAhai--hehim So to summarize, you have a preconceived notion about the level of personal freedoms afforded to citizens of the US, and this law conflicts with that notion, hence the law is wrong/unjust? Perhaps you need to recalibrate what you believe the level of freedoms are for the average citizen. Perhaps your views on how many freedoms are actually afforded to citizens are colored by vocal minorities in the US?

@uhoh If you read through, I was never questioning that tides are more complex than the basic picture or that tides at some locations can't be explained by a simple tidal bulge. My qualm was with the statement that tidal bulges don't exist.

Well I completely agree with you on the centrifugal force issue.

I think, all I was trying to get across is that the dynamic theory of tides does include that M2 term induced by the tidal forcing function. M2 does exist and is the largest component in tides. So as I said above, it seems misleading to me to say tidal bulges don't exist. They do, they're just tempered by other factors.

And honestly, I've never even seen a plausible explanation for how/why centrifugal forces could account for a bulge. Just bad diagrams and hand waving.

Exactly, I wouldn't say centrifugal force plays a part in the bulges. In fact, I get frustrated when I see diagrams that say it does.

And what I meant was, I think that I agree with you, but not with how you describe your point.

That just comes right out of the math.

I don't struggle with explaining two bulges

I don

I think this just all comes down to phrasing and interpretation.

Sorry, I keep interchanging tides and tidal bulge.

A better statement might be, while diurnal tides do exist, they're much more complicated than the simplistic image and you have to account for numerous, smaller scale effects to get a full, accurate picture.

I think its misleading and wrong to say tides don't exist.

In fact, they very wiki page you linked me says "In most locations the "principal lunar semi-diurnal", known as M2, is the largest tidal constituent, with an amplitude of roughly half of the full tidal ran"

But you can break the tides down into various constituents. The largest by far is the diurnal tides from the Moon. As I said elsewhere, I can agree that there are other constituents that may affect this and cause it to not be the simplistic image you'd see in a basic textbook, but those diurnal tides are still there, even they're damped by other factors.

But they are observed, in the mid-ocean the tidal bulge is about 1 m. I observe it every time I go to the beach. The high/low tides occur exactly when I'd expect them to based on the Moon's location. Where I live, the oceanic tidal bulges are not affected by other forces.

@DavidHammen Now I have to call you out. Are you talking about tides or tidal bulges! Tidal bulges 100% exist. That's just plain math and application of physics. I can agree that the tidal bulge may not always correspond to tides in the ocean for a variety of reasons like ocean currents, topology, etc. but the tidal bulge most certainly does exist. How could you explain the Moon moving away from the Earth, for example, if the tidal bulge did not exist? Furthermore, your linked question stating tides can't travel through water fast enough is faulty for the reasons one comment pointed out.

Okay, tidal bulge instead of tides then. My claim still stands. I don't believe that it doesn't exist.

@DavidHammen I don't believe that tides don't exist for a second. There are multiple issues I have with the answer you linked. Besides, if you just look around the web, you'll see extremely varying answers and opinions about tides so its a really hard thing to get a straight, correct answer on. Kind of like the question about what makes planes fly.

And all of this says nothing about the atmosphere. Once you throw that in, things get way more uncertain. You have to account for reflection of some small percentage of light into space and refraction of a good amount of the rest, depending on theta.

I doubt the human eye could notice a 10% difference. Keep in mind, I'm also talking about ALL radiation (UV, radio, gamma ray, infrared, etc) not just visible. And I don't think there's necessarily a name for that formula. It's just an inverse square law for luminosity fall off that accounts for the angle of incidence (theta)

And yes, theta will change with seasons, months, years, days, hours, and even by the second.

Depends on what you count as noticeable. From wikipedia: "rhe actual direct solar irradiance at the top of the atmosphere fluctuates by about 6.9% during a year". If you want this calculated to better than about 10% you're going to find that hard because the natural variability of the Sun over time is unpredictable.

Of course, if you're looking for accuracy you may be out of luck since L varies significantly (by several percents) over a variety of timescales (e.g., solar minimum vs solar maximum).

And I just realized math doesn't render in here so the equation, more readable, is (L/(4*pi*d^2)) * cos(theta).

Well, you can calculate the solar irradiance in the absence of an atmosphere and for a given, localized point on the Earth via $\frac{L}{4\pi d^2}\cos(\theta)$, where $L$ is the Sun's luminosity, $d$ is the distance between the Earth and Sun at the given time, and $\theta$ is the angle of the Sun from the zenith. You can get $d$ and $\theta$ from the ephemeris package with a little bit of work.

Not an easy one. At the very least, you'd need some sort of ephemeris package to calculate the precise location and orientation of the Sun with respect to the Earth at any given date/time.

You didn't really answer any of my questions. I can tell you that the solar constant is $1360\:\mathrm{W/m^2}$. If the sun is at an angle, you decrease it by the $cos$ of the angle the Sun is from the zenith. The main difficulty will be determining how it decreases as it travels through the atmosphere, which will be angle dependent and proportional to the $sec$ of the angle the Sun is from the zenith (to first order). This is not a simple problem with a simple equation and you should provide more information if someone is to help.

What do you mean by "amount of sunlight"? Do you mean the total irradiance? And do you want to account for the atmosphere? If so, your answer because much more complicated and prone to much more uncertainty.

@Timm I don't think there's any "standard" terminology given that no official organization like the IAU has set a standard concerning this. That being said, I've more commonly heard the usage implied by Polygnome, i.e., that we reside in the solar system while other star systems, which may or may not have planets, are referred to as stellar systems. It is true though that stellar system can more generally refer to a collection of stars, but often there are specific terms for specific types of collections, e.g., globular clusters.

@Barmar If there is, I've never heard it and can't find a reference to one. I think your best bet is to just leave off the prefix qualifier and call it a stationary orbit. Unlike terms like apoapsis and periapsis, there's no general prefix that I know of that you can prepend to stationary to make it mean a general case.

@Džuris I wouldn't expect so, but I can't be sure without more research. My suspicion is that if a body was orbiting at the selenostationary orbit, it'd be high enough that the mascons wouldn't have a noticeable effect.

To be fair, you'd use the prefix for $10^9$ instead of $10^{11}$, so that $1\:\mathrm{AU}$ is just $150\:\mathrm{Gm}$. Although $1\:\mathrm{AU}$ is certainly more intuitive than $150\:\mathrm{Gm}$.

I didn't mean to start such a metaphysical debate. I think ultimately KenG is correct in stating that we can make no claims about the entire universe and thus the only statement we can make with any certainty is on the observable universe. Saying the entire universe is flat is technical an unprovable statement. However, I have to agree with John Davis in his statement that it is reasonable to assume the larger universe is not any different from the observable one. Without evidence to the contrary, I think it's reasonable to suppose the entire universe is flat just as the observable universe is

I'm sorry, but I still believe that our measurements of the flatness of the universe (despite being made on the observable universe) apply to the entire universe. This is at the very least backed up by Wikipedia (I know that's not the best source). I'd readily accept any sources you have to the contrary though!

Yes it is, but we can make statements from it about the entire universe such as the flatness. I've never heard anyone state that the flatness we measure applies only to the observable universe.

Our measurements of the flatness of the universe don't depend on which parts of the universe we can see. They derive from measuring CMB and apply to the universe as a whole, not just the portion of the universe we can observe.

Carl Witthoft makes a good point. It's only dark in the visible range. It wouldn't be dark in other wavelength regimes.

@LightnessRacesinOrbit I don't think so. It is true, there is no established method for how terrestrial planets can form free from a star. At best we've found rogue "super-jupiters" which may be nothing more than ejected planets. As far as we know, Earth could not have just formed in place, sans star, I know of no model or hypothesis explaining how it could.

@MatthewWhited Yes but the Earth is pretty well dated to about 4.53 billion years old and with a pretty specific metallicity. Just because lots of rogue (and not necessary terrestrial) planets could have formed in the age of the universe, that doesn't mean many of them could have been Earth.