The 23-year-old Newton spent that time studying and laying the foundations for his greatest work, the Principia. One day he sat thinking in his garden, when an apple fell.
Then he realized. The direction the apple fell, along with every other object on this round earth, was always toward Earth’s centre. It wasn’t just that the apple fell, but that it tried to go to Earth’s center. That was Newton’s Eureka Moment.
he also posts about NASA's twin study.
The study focuses on four categories of research split into 10 investigations to evaluate identical twin astronauts Scott and Mark Kelly. These investigations provide broader insight into the subtle effects and changes that may occur in spaceflight as compared to Earth. This is done by studying two individuals who have the same genetics, but are in different environments for one year.
Gizmodo article here: Mark Kelly is now a bit older than his twin..