Sounds to me like you're seeing heat haze in the summer, very common down here In Australia.

So you're saying that because our mass isn't fixed, every time it changes we more or less move to a new orbit relative to our common center of mass? Is that basically correct?

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the north east is run on crappy servers so we need water vapor to reduce draw distances or we get frame lag, the south west has much better servers so they get the full draw distance without the need for performance improvements granted by the fog.

Yup. Except that there is no expansion of space between our two galaxies. As miniscule as it is, the gravitational "force" is much stronger than the expansionary forces so that rate is 0.

We are in the Laniakea Supercluster and the space between our Supercluster and the next one, Perseus–Pisces Supercluster, are expanding at 73km/s. Within Laniakea, the gravitational "force" keeps us together in the same orbit. Everything is orbiting something.

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Edit: 73km/s/megaparsec

There's amble evidence that the Milkyway has collided with another galaxy and currently is in the process of incorporating another galaxy into its structure. The other galaxies are drawf galaxies so we maintained out spiral structure. With Andromeda we will not be a spiral any more.

Andromeda is slightly larger and it and 29 other galaxies (including the Milky Way) are part of the Local Group of galaxies. There may have been many more galaxes but they have since been incorporated through glactice mergers. Andromeda and the Milky Way's orbits around our center of gravity will bring about a merger in the distant future. By that I mean one of these galaxies are not in the stable orbit (on galactic time scale). Even after the merger the combined mass and velocity of the the merged galaxies will put us into a different orbit around our center of gravity.

You know what they say: If Andromeda doesn't come to us, we will come to Andromeda.

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The observable universe is not infinite. And it keeps expanding such that more and more of it is not visible. But that's just because we're limited by time and the speed of light with respect to what we can see. If you went to the edge of the earth's observable universe you'd probably just find more universe. You'd be at the centre of a new observable bubble with the earth and a portion of the earth's observable universe bubble in one corner. As you move anywhere the "observable universe" moves with you. You take a step left and now the observable universe is one step larger to the left (though it's expanding faster than that so you wouldn't see anything new). Make sense?

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It's not exactly like raisins in a loaf, though that's a good way to explain it to layperson. Unlike a loaf of bread or surface of a balloon, there isn't a firmament in which galaxies are suspended, and only the firmament expands such that they never touch. It's more like an infinite stew that keeps getting infinitely watered down - slowly. Sometimes the bits in the stew will still hit each other as everything cooks and swirls. They'll just do it less and less often as more water gets added.

> After a certain distance, things are moving away from us faster than the speed of light. Those objects are unreachable to us now

That's a common misconception. We see things where the distance to them always increased faster than the speed of light. The matter that emitted the CMB we see today is an example. The number of things we can see is still increasing as the universe gets older.

In the distant future, in a universe completely dominated by dark energy, your statement will be right.

Wow that's incredible! If I understand correctly that means the light being emitted from an object is one long stream and we can access different segments of it by tuning into different frequencies?

Gravitational forces do indeed weaken with the square of the distance, but they strengthen between more massive objects. You also need to factor in the relative velocity between the objects.

Just for a complete picture, the Andromeda galaxy is about 2.5 million light years away from the milky way (~0.9 Megaparcecs), and moving towards us at about 110 km/s. The expansion rate of the universe is about 73km/s per megaparcec.

While this is probably a massive oversimplification, we can think of the Andromeda galaxy receding from us at about 73 * 0.9 = 65km/s, but is moving towards us faster than it's receding, at 175km/s, but the expansion rate of the universe brings its net speed down to 110km/s. This is just a snapshot in time, since as the distance gets smaller, the force of gravity gets stronger, and there's less expansion of the universe to deal with. In other words, Andromeda should be accelerating towards us over time, assuming just gravitational force and the expansion rate of the universe.

Why didn't Andromeda and the Milky way already merge? Basically, both galaxies were originally two separate denser regions in space that were far enough apart to form two independent galaxies, but close enough to not recede over time thanks to the expansion of the universe.

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So that’s why the stars look clearer on a cold night! Thanks for the explanation.

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That's the cool thing about infinity. There is no end. You can always add 1 one more.

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