Today, for the first time in history, humans can see the entire sun.
In October 2006, NASA launched a pair of twin spacecraft into space. Called STEREO — Solar TErrestrial RElations Observatory — they traveled in opposite directions, one ahead and the other behind the Earth in its orbit around the Sun. The goal was to get a wide, stereoscopic view of the Sun which would provide 3D information on our star.
Today they reached that goal. After traveling a combined 470 million kilometers (290 million miles) relative to the Earth, they are now on opposite sides of the Earth’s orbit, staring down at opposing faces of the Sun.
The full coverage observation of the sun will last for eight years. Dr. Phil Plait has an explanation of how NASA did this, and why it is important, at Bad Astronomy. Link