# Is the Earth Rotation also simulated?

Hi guys,

Today at a night flight i asked me is the Earth Rotation simulated in the MSFS 2020? Because its clear to me when the sun goes down the earth rotaded. but its also in the msfs 2020 so? Or is in the MSFS 2020 only that the Sun goes up and down without the Earth rotation to make a illusion of a sunrise and sunset to us simmers? What do you think?

regards

Legendsy

Legendsy

the earth rotates, I had the experience to leave France at nightfall and to catch the sun with the typhoon, so yes the earth rotates

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That sounds awesome. So just load at nightfall in paris for example and head East(?)

I’d love to try that out!

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Earth is flat… JUST KIDDIN

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Well, the sun, moon etc. are moving like their real counterparts along the sky.

The definition about whether they are moving or the earth is rotating is a bit different in a simulator than it was for Niklas Koppernigk back in the days.
The sim might move objects to give a realistic illusion of the objects in the “skybox”.

But in terms of simulation, the result is pretty realistic an that’s what matters.

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small video where I ran after the sun so that it does not set
Originally, I started the flight at sunset, almost at night from France to the USA, with the Typhoon
run after the sun

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Yes when they only moving the moon and the sun. But they called they would make a twin of our real planed and for me that includes everything that makes up the planet. And that is also the earth rotation etc.

after concerning the physics of flight, I do not know, to make a Paris or London to NY or NY to London or paris, is it the same time, according to the winds and the rotation of the earth, good question, can be that in the game it is the sun which turns around the earth

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He means that the frame of reference may be different but the effect is the same.

Yes, the earth’s rotation is simulated in MSFS.

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if the earths rotation is simulated, does this also mean the coriolis effect is catered for also? doubt it

i think the limit of simulation of earth rotation is purely linked to geometry of celestial objects and the reality is that these objects are actually spinning around the sim earth from a fixed distance (eclipse not properly modelled)

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Exactly, for simulations you try to only do what is necessary for the simulated aspect.

There are mathematical models to calculate the position of the sun and moon and planets on the night sky at a certain position and time on earth that don’t require you to physically simulate their whole movement.

What is more important is that the earth’s curvature is simulated. It can be dark at ground level but if you quickly move your aircraft higher up into the sky, you’ll see the sun and the earth’s shadow along the horizon. Pretty cool and very realistic.
Again it doesn’t mean that they actually create the whole globe all the time, they could just model the visible part of it (means, until the horizon at least) but it’s sufficient for that matter.

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Doubt it as well, but neither would be dependent in a simulator.
You can simulate coriolis without actually simulating the earth’s rotation. And you can simulate the earth’s rotation without coriolis.

It’s all a matter of abstraction since you can’t simulate every atom/particle, you focus on what’s important for your simulated environment.

With real world data streamed into the sim though, you still get the impact of coriolis effect in terms of weather without the need of simulating (calculating) it.

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There is an important concept in computer graphics and simulations: „Fake it till you make it!“

And that is absolutely the right think to do (in computer games): it does not matter whether the Earth polygon rotates (and possibly even moves around the sun), or simply the „skybox“ is rotating.

All that counts is the „illusion of being as close as possible to the real thing!“ aka „it looks good, so it works!“.

Unless of course FS 2020 starts simulating space travel…

Well it does, even for MSFS since rotating a skybox would result in static positions.
It actually moves the objects (or textures/lightsources?) independently along the sky But probably you mean it that way.

You can also see different moon phases, but I don’t think they simulate the sunlight actually hitting a Moon object and illuminating it from the side, but rather simulate the phases in a simpler way since you can calculate the moon phase with a much simpler algorithm and thus less computational effort.

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Uh… yes, I was „over-simplifying“ a bit. What you said

My point was rather: „you cheat where you can“ in computer graphics/physics - why? To save precious CPU/GPU cycles - and memory!

So you „bake light textures“, precalculate shadows (where possible), fake wind by simply moving grass polygons… you get the idea.

Of course a LOT of flight physics are actually done „for real“ in FS 2020. But especially when it comes to visuals the répertoire of „fake tricks“ is immense And that is absolutely okay, for as long as it „looks and feels good“.

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CaptSeppi is streaming on Twitch and he tested this on Sunday. After a 11 hours long flight only navigating by the Sun, he hit Hawaii straight on. Pretty impressive by both him and the Astro model in MSFS.
He used the Celestial Navigation mod and “shoot” the sun every hour and did course corrections based on that. He corrected for the Coriolis effect, but I am not sure how big impact that had on the end result.

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I’ve wondered this, myself. There’s a bug report here:

that has often made me wonder if the sun just drops below the horizon but never quite past astronomical twilight.

It’s easy to presume that the earth is still and they make the sun and moon (and stars) rotate around it.
Can you imagine the issues and bugs that would be implied having a rotating earth with weather data , clouds , wind , and having the whole scenery being in a constant movement … much easier to program a moving sun and a moving moon in my opinion. I would go as far as betting tons of cash on this haha. It just makes more sense !!

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