Unless you lived under a rock during the past week, I'm sure you heard about astronaut Scott Kelly and his crew returning back to Earth from a year-long expedition in space. Stories about his expedition have been posted all over social media, from news websites and blogs to Facebook and Twitter . The thing is, most of them are about what he did in space and how he arrived back to Earth, but not about how this trip makes him a hero. Well, not to worry, because I can tell you exactly why!

To start off, it's important to know that he is much more than an astronaut. In fact, Kelly is also a retired Navy Captain who served for 25 years, and a father. He attended the University of New York Maritime College in 1986 to earn his B.S. degree in Electrical Engineering, and then received his commission via the Navy Reserve Officer Training Corps (NROTC) a year later. After becoming a Naval Aviator at Naval Air Station Chase Field in Beeville, Texas, he received his M.S. degree in Aviation Systems from the University of Tennessee. By the time he was 32 years old, Scott Kelly was working for NASA and preparing for his first mission to space. And if that wasn't enough, he was also raising two daughters who are teenagers now!

Besides that, what makes astronaut Scott Kelly a hero is why he was in space for the last year. For those who don't know, the main goal of his year-long expedition was to understand how the human body reacts and adapts to the harsh environments of space. The data collected during the past 12 months will be compared to Scott Kelly's identical twin brother's, Mark Kelly, who is also an astronaut. Since Mark Kelly stayed on Earth while his brother explored space, he is the "control" subject and will play a key role in identifying the differences between him and his brother .

This research will help NASA learn about the health concerns that astronauts are at risk for while in space, and will ultimately help those who go on future missions around the moon, an asteroid, and Mars. In other words, if it weren't for Astronaut Scott Kelly, none of these scientific advances would be made and future astronauts would continue to be unsure about what traveling in space can do.

Furthermore, what makes Astronaut Scott Kelly special are the things he agreed to do while traveling in space. For example, can you believe that he drank around 730 liters of recycled sweat and urine? That's about 1,640 regular sized Poland Spring water bottles! And if that's not enough, he also exercised for 700 hours to keep his heart, muscles, and bones strong (or at least as strong as they could possibly be in space, which is not very strong). Even with that much training, Kelly still lost a ton of bone mass and needed help walking immediately after landing on Earth. Finally, Scott Kelly encountered massive amounts of radiation that is equivalent to what a person flying from New York to Los Angeles 5,250 times would experience (AOL). This unfortunately increases the risk of cataracts in the eyes and cancer in the body (NBC News). Clearly, Kelly really cares about his job!

So as you've probably realized by now, astronaut Scott Kelly is a very accomplished individual who has dedicated a large portion of his life to the Navy and to NASA. If it weren't for him and his brother, Mark Kelly, scientists working at NASA would not be able to learn more about the human body in space and make ground breaking history. People who sacrifice their life to seek more knowledge for the world deserve the utmost respect and appreciation. Needless to say, Astronaut Scott Kelly and the rest of his crew are definitely these people!

Finally, if any of you are as interested in astronaut Scott Kelly's journey as I am, I definitely recommend looking him up! He has 1,000 photos from space on his Instagram and a documentary series called "A Year In Space" on Time Magazine's website. The documentary truly opened up my eyes to how brave astronauts are, so I highly recommend it. Plus, to show you how awesome his pictures are, here is a great selfie he took with planet Earth!