He'll be blasting off in December and will spend six months on-board the International Space Station (ISS).
So, we thought now would be a good time to tell you our top astronaut facts...

Gwynedd council is a considering charging a premium on holiday homes.
Councillor Jason Humphreys, however, fears the authority will lose out as people sidestep the charge by classing their second homes as self-catering businesses.
Gwynedd said it was powerless to stop owners making the change.
Some Welsh councils have voted through hikes in council tax charges for second homes, including Anglesey and Pembrokeshire, with other councils still consulting on a change.
Since 2006, the number of self-catering units in Gwynedd has risen from 78 to 968.
Changes to the Housing (Wales) Act 2014 mean councils have the ability to charge a premium on top of the existing council tax payments for second homes from the 2017-18 financial year.
But self-catering units are classed as businesses and so their owners pay business tax to the Treasury rather than council tax.
According to the law, self-catering units have to be made available for letting for 140 days a year, and owners have to prove they have been let for at least 70 days.
Mr Humphreys, chairman of the council's corporate scrutiny committee, told the Post Cyntaf programme there was no mechanism for monitoring the situation.
He called for AMs and MPs to demand a law change to make it compulsory for anyone seeking to reclassify their holiday home as a self-catering unit to apply for planning permission.
But Peredur Jenkins, cabinet member responsible for resources, said the council had no power to stop owners from designating their properties as self-catering units.
The council previously warned the potential "loophole" could leave authorities worse off.
Mr Jenkins said Gwynedd was pressing the Welsh Government to consider changing the planning regulations to give local authorities the power to determine whether owners could re-classify their properties.
The Welsh Conservatives have criticised the second home tax as an unfair "money-spinner", with shadow local government minister Janet Finch-Saunders calling it a "spiteful wealth tax".
She said it was a "a direct tax on people with second homes, many of whom already pay twice for services they rarely use".
An estimated 23,000 homes in Wales are empty or used as second homes.

Based on CT scans, the organs are fitted into a realistic synthetic "body" and connected to pumps which mimic human breathing and blood flow.
Nottingham Trent University, with the NHS and Ministry of Defence, used silicone gels to replicate the feel of human tissue.
Bespoke models could now be created to prepare for individual operations.
Richard Arm, of Nottingham Trent University's School of Art & Design, said he was asked to come up with a heart model for a surgeon who wanted to practice performing an implant.
He said: "When making more organs, the trickiest part was the flexibility.
"The heart has 17 different 'hardnesses' so 'does it feel right?' turns out to be a bit vague.
"Then we put them together and I knew we were getting it right when I started to feel sick."
The prototype - officially known as a thoracic trauma trainer - will be exhibited to trauma treatment experts.
After feedback, two models are due to be produced for the MoD by December 2017.
Colonel Peter Mahoney, emeritus professor at Defence Medical Services, said the requirement was for training equipment that was portable, robust and reusable, while "also achieving a realism" that had only previously been possible with dead bodies.
He added: "We wanted to start with the chest, because it is a common area connected with trauma, but if it could be created with realistically-moving lungs and blood vessels then any other body parts would be possible."
Future developments could include the brain, eyes, stomach, pancreas, liver and kidneys, the vascular system in a person's legs and bespoke models for patient-specific preoperative surgical planning.
The European Space Agency's first British astronaut, Tim Peake, is completing the final preparations before his mission to space.
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Calls have been made for a law change to stop second home owners avoiding additional council tax by turning their properties into self-catering lets.
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Life-like body parts have been 3D printed to help army surgeons deal with trauma injuries.