I actually think the other photo you link does it make it clearer, in the opposite way.
That photo shows the top bright circle clearly partially obscured by another dark circle of the same size. The only explanation is it's a partial eclipse of the sun by the earth. Nothing else produces that shape. And indeed, other photos show a full eclipse and are labeled as such, so we know that the timing is right! The shape is clearly defined -- it's not bloom or lens flare. Which means that above the horizon we see both earth and sun. And in the hero image, we see the same thing, as you describe it "a little bit of flatness". But that shape can't be produced by blooming a crescent. It's answered by your linked photo -- it's the dark, black earth obscuring the edge of the sun.
Which leads to my original question -- what the heck is the brightness touching the horizon of the moon? It simply can't be the sun. Also, the way it dips below the horizon shows that if it is real, it actually has to be nearly entirely "bloom". But then the sun above should have way more bloom and it doesn't... which means it isn't a real object at all, not even a real reflection you'd see on the lunar surface.
So I did a little bit more digging and it turns out this is a common effect in camera lenses, duplicating the sun. It's not lens flare exactly, but it's the same idea. Examples here on earth:
So this isn't sunset. The sun is above the horizon, and the bright "sun" touching the horizon is a reflection of the sun in the camera's optics. It doesn't exist in reality.
That photo shows the top bright circle clearly partially obscured by another dark circle of the same size. The only explanation is it's a partial eclipse of the sun by the earth. Nothing else produces that shape. And indeed, other photos show a full eclipse and are labeled as such, so we know that the timing is right! The shape is clearly defined -- it's not bloom or lens flare. Which means that above the horizon we see both earth and sun. And in the hero image, we see the same thing, as you describe it "a little bit of flatness". But that shape can't be produced by blooming a crescent. It's answered by your linked photo -- it's the dark, black earth obscuring the edge of the sun.
Which leads to my original question -- what the heck is the brightness touching the horizon of the moon? It simply can't be the sun. Also, the way it dips below the horizon shows that if it is real, it actually has to be nearly entirely "bloom". But then the sun above should have way more bloom and it doesn't... which means it isn't a real object at all, not even a real reflection you'd see on the lunar surface.
So I did a little bit more digging and it turns out this is a common effect in camera lenses, duplicating the sun. It's not lens flare exactly, but it's the same idea. Examples here on earth:
https://www.reddit.com/r/Damnthatsinteresting/comments/15dj3...
https://www.reddit.com/r/atoptics/comments/1cqk6dv/took_sunr...
https://www.metabunk.org/threads/explained-two-suns-sanibel-...
So this isn't sunset. The sun is above the horizon, and the bright "sun" touching the horizon is a reflection of the sun in the camera's optics. It doesn't exist in reality.