The Venus and Mercury misunderstanding

Random drawing from the web
(all out of scale, for the record)

Flat earthers and people with a partial understanding of astronomy may say that from earth you couldn't see Mercury and Venus. (so, somehow these 2 planets are a lie? I'm not sure what's the full picture behind this idea) 

But why they say so?

Because if it's night time, you are on the opposite side of the sun, and since Mercury and Venus are near the sun, on the "day side" then you couldn't see them.

Something like this:

The man in the night side is confused! Where is Venus?
Click to enlarge

Now this doubt is legit. Every kid and every adult with no familiarity with the night sky could have this same concern.

So, how come you can see those 2 planets?

Well, it's simple: what you see in that drawing it's the midnight, but the earth doesn't have 2 sides only, mid-day or mid-night! 

Actually, because it's round, it doesn't have sides at all. And people don't only look straight up, but in many directions.

In fact, when you look at the sunset, you are not looking up at all, but down over the horizon.

There isn't only "up" to look at
Click to enlarge

 So, back to Mercury and Venus, let's make the drawing prettier:

Click to enlarge

As you can see, now it makes more sense.

But let's add more details to it.

For example, the two guys are necessarily near the sunset and near the sunrise. Certainly for them it can't be midnight. Right?

Midnight is exactly from where we started, thinking that you cannot see the 2 planets. And in fact, you never see those 2 planets at midnight. You can see Venus and Mercury just before sunrise and after sunset. 

Check this Mercury timetable from the in-the-sky.org website (for this week, Sydney - Australia):

Mercury timetable - click to enlarge

And the sun:

Sun timetable - click to enlarge

And this is the animation of those timetables, from the Timeanddate website (at the time of writing, from Sydney - Australia):  

As you can see, right now, from Sydney, you only have a short time after sunset to spot Mercury before it goes over the horizon as well. And in the morning, it comes up after the sun, so it will be already too bright to see it. Not possible!

(and by the way, the other bright spot at sunset is Venus)

Then over time the planet and earth will move around and it may be easier at sunrise than sunset. It all depends on the relative position of earth and Mercury around the sun.   

Same applies to Venus. With the only difference that Venus is further out from the sun than Mercury, so it is higher in the sky, and you have more time to see it. Just never at midnight!

And another thing.

In my modified drawing, the guy on the left look at Venus with an angle. And he can see the side in the dark, Right? 

In fact, if you look for photos of Venus from earth, you will only find Venus looking like the phases of the moon, just never "in full" (because in that case it will be on the opposite side of the sun, then completely hidden from view). 

A photo from earth of Venus, looking always like our moon.

Timetable for Venus - click to enlarge