Starliner: How will the astronauts return to Earth? NASA faces a tough dilemma
Suni Williams and Barry Wilmore were supposed to stay on the ISS for only one week, but they have now spent three months in space
Boeing’s Starliner: Astronauts stranded on the International Space Station, NASA says they can return
The mission was supposed to last eight days
A second Earth has been spotted by NASA scientists but it is 40 light years away
The exoplanet, called "Gliese 12b", is slightly smaller than Earth and could be habitable