Are they planning to cover several hundred miles of area with a dome? Because astronauts are probably going to recognize constellations, and and then there are also satellites that will tend to be visible in the early evening/morning.

@notovny: Any educated person will recognize at least a handful of conspicuous constellations; for example, Ursa Major, Ursa Minor, Cassiopeia, and Orion consist of bright stars and have unmistakable shapes.

Come to think of it, there's also a pretty familiar Moon up there, too.

@AlexP: He’s only going to keep up the illusion for the day

@notovny: The illusion will only be kept for a day

@AlexP Plenty of educated people don't know what constellations look like.

@Acccumulation: All right, make it a well educated person.

@Acccumulation Not people whose literal job partly relies on astral navigation.

The sun would be the same. The gravity would be the same. There was a Twight Zone episode which dropped the astronauts onto a desert, and only after somebody killed the others for their water did he realize they were within a few miles of the b'day.

Wherever it was that we faked the moon landing.

@AlexP Your position is increasingly a No True Scotsman and elitist. Knowledge of constellations is trivia, and not needed to be "well educated".

@user3482749 I wasn't responding to a comment about astral navigation. And in the days of GPS, who relies on stars?

@Acccumulation You're kidding, right? What elementary school student doesn't know at least a couple of constellations? Seriously. You just pick this stuff by being growing up in a human society around books and media. You're talking about it as if it were calculus which has to be explicitly taught.

FYI, you need to make sure that there’s no plane flyovers visible too.

This whole discussion about constellations is silly because the OP already said the illusion is only for during the day. But I can tell you there are plenty of educated people that don’t know jack about the constellations, especially if they grew up in a city or densely populated country and only a few bright stars are visible.

@Acccumulation as a counterpoint, in the days of GPS, who wouldn't notice that their GPS was still working?

@Acccumulation People whose job involves leaving the earth. Like, you know, the astronauts that you're trying to fool.

I think you could use any old quarry in England ;)

What is the world building content of this question?

And the Moon is WAY harder not to recognize than constellations. And you can see the moon during daylight.

Remember the moon is visible during the day. A half moon is visible roughly half the day and half the night, a quarter moon, for three quarters of the day and a quarter of the night. Only the full moon goes up as the sun goes down.

These astronauts aren't going to look up and notice that the clouds are the same and that the sun looks the same and a matter of fact the sky still has the same blue color? Also that they didn't spend years in transit like relativity tells them they would have to in order to get anywhere near another planet?

With regards to the constellations it might suffice to transport them to the negative of their latitude, unless they were originally from near the equator. For many (most?) people in either hemisphere above/below +/- 30 degrees, the opposite hemisphere would likely be unrecognizable.

@Michael Yes, I imagine this is true for someone who has never gone out of their way to look at an astronomy book as a child. Astronauts though...seems rather unlikely.

@DKNguyen in many major urban areas modern elementary school students would not be able to see most of the classic constellations because of light pollution. They might have read about them in a book, but they would not be able to match them to reality which they can[not] see themselves at night without traveling to the countryside.

Is seeing constellations enough to know you're still on earth? If, for example, you were on Mars, would you be able to recognize the same constellations?

@Anon Yes, pretty much anywhere in the solar system, the constellations are not going to be so different that you wouldn't recognize them. The only star whose position would be obviously different would be the Sun...

@Peteris True but I saw pictures of constellations in a book and on TV far before I ever actually saw them in the sky.

@Anon That's a good point.

I'm afraid hiding plants would make oxygen content of air even more suspicious.

On earth your major issue is radio signal. They are everywhere, you can build a normal radio with a speaker and some copper wire. It's a 9 years old DIY. Radio and gps will be avaidable everywhere. No matter what you choose warp it in few layers of plastic bags.

The oxygen issue mentioned by @Pere is the give away in most sci-fi when they create breathable environments without plants (dry, cold, dark).

If Doctor Who taught us anything it's that any old rock quarry serves great as an alien planet

Hmm