NASA astronauts Sunita "Suni" Williams and Barry "Butch" Wilmore have reached their six-month milestone of being stranded on the International Space Station, despite initially planning to stay for just eight days.

Two stranded NASA astronauts have followers scratching their heads over a festive new photo that shows the space travelers getting into the holiday spirit.

The crew launched to the ISS in June for a week-long mission but will end up spending an unplanned nine months in space.