They seem easy to distinguish, but NASA has had some trouble figuring out which is the sun and which the moon.
NASA recently tweeted the following in August...
It passed unnoticed that this is actually the moon in the picture.
That was August 12. But then again on September 8 they made the mistake on another picture from the Space Station. This time eagle-eyed Twitter users spotted that there was a difference between the two bodies.
NASA quickly deleted the tweet, but not before it was captured by another Twitter user.
It seems pretty easy to differentiate between the moon and the sun. The question is where were the recent picture of Pluto really taken? Could this explain why the mini-planet looked so unexpected?