NASA Astronaut Mike Hopkins, who holds a masters degree in aerospace engineering from Stanford University, tweeted the ultimate portrait taken while he was on a spacewalk outside the International Space Station on Christmas Eve, Dec. 24, 2013.

Hopkins has been tweeting from space, and said this about his photograph: "Wow...can't believe that is me yesterday. Wish I could find the words to describe the experience, truly amazing''.

NASA said that Hopkins, Expedition 38 Flight Engineer, participated in the second of two spacewalks designed to allow the crew to change out a pump module on the exterior of the International Space Station. He was joined on both spacewalks by astronaut Rick Mastracchio, whose image appears in Hopkins' helmet visor.

You can follow Hopkins at @AstroIllini