Conor Kearney, the YouTuber who strolls across video game maps to estimate their real-life scale, can't really hike to the center of the galaxy in No Man's Sky. But he can walk across a planet and get a sense of one's real size relative to the player.
The long story short is that a world in No Man's Sky is a very large place to explore but it's not exactly planet-sized, as in real life. It took Kearney 11 hours and 50 minutes to walk almost halfway around the planet he chose. If one assumes his walking speed on it is 3.1 miles per hour, as the average is on Earth, that planet is about 74 miles in diameter.
Of course, a planet that small — our Moon's diameter is 2,159 miles — would have a lot less gravity than Earth and that would definitely affect one's walking pace.
Kearney pointed out that Hello Games founder and No Man's Sky creator Sean Murray, in his appearance on The Late Show with Stephen Colbert, said the game would feature "planet-sized planets." I realize that 74 miles is not even close to the diameter of Ceres, the smallest dwarf planet (587 miles) in our Solar System. I still think, within the confines of a video game — certainly one that has 18.4 quintillion of these babies — that taking 24 hours to walk all the way around one qualifies as enough of a planet-sized planet.
Kearney told me he'd probably walk around a moon in No Man's Sky next week to get an idea of how big one of those are. I think I would have had enough at this point. Let's pause to consider that Kearney walked in a video game for nearly 12 hours, for science. And now we know roughly how big a No Man's Sky world is. The answer: big enough.