From thinking the Earth is flat in ancient times, and first ideas of spherical Earth in 6th century BC to this beautiful photo taken 1972.
By NASA's Apollo 17 crew, 1972
It's a common thing for most people now, we even have Google Earth, but just think of it...we saw a quality image of Earth just 40 years ago.
This photo is commonly name as "first Earth image", however, there were more earlier ones, nor-readable i'd say.
V-2 Rocket, launched on March 7, 1947, took this picture from 101 miles up. The dark area at the upper left is the Gulf of California.
They even shot a video :)
Here is another pic from NASA (who else can it be :) )
Dated 2001 - 2002
As you can see, Earth becomes more colorful :)
And those are my favorite, night pics: