I have always been an astronomy nerd ever since I was in middle school. I have spent countless nights in my back yard with my telescope and star chart, peering into the night sky with endless curiosity and wonder. I would gaze at the constellations wondering what was "out there" in space and marveling at our small place within the universe.

But what I truly found fascinating, almost more than space itself, was the astronauts who made it their livelihoods to explore the final frontier and adventure where no man has gone before. Astronauts can come from a variety of backgrounds, from air force pilots to engineers to medical doctors. They can have a passion for music, photography or even yo-yo tricks.

Of course astronauts are incredible scientists, but they are fascinating people as well, often with great life stories. So, here are 7 astronauts you should know about.

1. Don Pettit

Don Pettit is an awesome astronaut who has become known for his beautiful photography skills. He has also been known to make some pretty awesome YouTube videos, including one where he shows his cool yo-yo tricks in microgravity.

2. Mike Massimino

In addition to some pretty awesome cameos on The Big Bang Theory, Mike has written an awesome autobiography titled Spaceman, which I highly recommend. He has also made some fantastic appearances on Craig Ferguson's late night show.

3. Chris Hadfield

Chris Hadfield was the first Canadian man to walk in space. He is also a stellar musician and has even recorded music videos in space!

4. Scott and Mark Kelly

Chris and Mark Kelly are identical twins with the same job! Chris spent a year in space aboard the ISS while his brother Mark is now running for the United States Senate.

5. Samantha Cristoforetti

Samantha is an Italian astronaut from the European Space Agency who has spent nearly 200 days in space. This has made numerous YouTube videos from the ISS including this piece by CNN.

6. Sunita Williams

Sunita Williams is an American astronaut who is currently training to fly NASA's new spacecraft for their Commercial Crew Program. She has also made a superb tour of the ISS that you can watch here.

Karen Nyberg was the 50th woman in space and also has some great videos in space, including this one on how astronauts exercise on the ISS.