The tantalizing twin paradox effect that's popular in Physics' books will soon become a reality. At least, the part where one twin goes to space will.

U.S. astronaut Scott Kelly will be flying next month to live on the International Space Station for a year.

Meanwhile, his twin brother Mark will stay on Earth while NASA observes how space travel affects the body of his brother in space.

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Researchers will be observing how spaceflight affects the human body, including the cardiovascular system, DNA alteration due to environment and responses of the immune system.

The study will also compare the twins' ability development throughout the experiment in terms of decision-making, spatial ability and memory.

According to Einstein's theories, Scott will age slightly slower than his twin during his stay in space. Thus, the so-called twin paradox effect.

As Scott will be far from traveling too slow compared to the speed of light, he will have aged only milliseconds slower.

Mark has commanded two shuttle missions. During his last flight, he commanded the Endeavour that was also on its last flight.

Soon after, he retired to aid in the recovery of his wife from an assassination attempt.

Scott had his first space flight in 1999. He has spent more than 180 days in space.

Russian cosmonauts Mikhail Kornienko, a space veteran who has spent about the same number of days in space as Scott, and Gennady Padalka will be joining Scott in his flight.

They will be riding the Russian Soyuz, which will launch from Kazakhstan on March 27. 

TagsTwin paradox, NASA, Twin experiment, kelly twins, International Space Station