Trust me! It was dark in any part of Europe that matters when that shot was taken. Sure the sun was visible above the arctic circle but really, do you think he's tweeting and taking pictures up there?
The shot was 2 hours old at 6:11 pm Pacific time.
That was 1:11 am in Amsterdam, Solar altitude was -14.47 degrees.
That was 12:11 am in London, Solar altitude was -14.76 degrees.
That was 1:11 am in Oslo, Solar altitude was -7.27 degrees.
That was 2:11 am in St. Petersburg, Solar altitude was -6.16 degrees.
That was 11:11 pm in Reykjavik, Solar altitude was 1.27 degrees (too low to make the shadows as seen in the shot).
Just take a look at the Earth shadow curve and you can see where it was dark.