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It's a big year for Nasa as the world-famous space agency celebrates its 60th birthday.

To mark this landmark anniversary, we're taking a look back at where it all began.

Nasa was was officially founded by Congress - the part of the US government which writes and brings in laws - on 1 October 1958.

It was created because the Americans wanted a dedicated space agency that would put them at the forefront of space exploration.

Its predecessor was a US government agency called the National Advisory Committee on Aeronautics (Naca), which would eventually become Nasa as we know it today.

Nasa stands for National Aeronautics and Space Administration. It is probably most well known for its ambitious missions into space, but it does a huge amount of work researching and developing new planes to be flown here on Earth too.

Doug Millard, a space expert from the Science Museum in London, explains: "Nasa is the biggest and most powerful space agency the world has even known, playing leading roles in all aspects of space exploration and especially human spaceflight and the robotic exploration of the Solar System."

Humans have always had a fascination with being able to fly. The National Advisory Committee on Aeronautics (Naca), formed on 3 March 1915, wanted to explore just what we could do.

At the beginning of the 20th Century, we were still working on getting off the ground in the first place - and staying there! The Wright Brothers made the world's first manned, powered flight in December 1903 - but it only lasted 12 seconds.

Once engineers had mastered keeping us off the ground (planes advanced hugely during World War I), Naca's main goal was to make aircraft that could travel at faster speeds than anybody had been able to fly before.

By the 1930s, engineers were finding that planes powered by piston engines and propellers couldn't function properly above speeds of around 350 mph, so they needed to do more work if they were going to make planes that could go at super speeds.

This marked the start of Naca's X-plane development programme - 'X' meaning 'experiment' - which would give engineers knowledge and understanding that would prove vital for America's space programme.

By the end of the 1940s, Naca carried out its first manned flights on its X-1 plane and on 14 October 1947, Air Force Captain Chuck Yeager made history in an X-1 by flying faster than the speed of sound.

Work continued and by the 1950s, Naca was working with the US navy and air force on an aircraft called the X-15. Its ultimate goal was to develop a plane that could function not only at supersonic speeds, but also at extremely high altitudes - and engineers were dreaming of space travel.

"In the X-15, we have all of the elements and most of the problems of a true space vehicle," explained Harrison Storms, who worked on the plane.

But while the Americans had been developing X-planes, the Soviet Union - a group of states led by the Russians - was busy on its own space programme.

On 4 October 1957, disaster stuck for the Americans. The Soviet Union devastated the Americans when they launched the satellite Sputnik - the first man-made object to go into orbit around the Earth - and Sputnik II followed a month later. The Russians had beaten the Americans to space.

This marked the start of what is now known as the space race - a race between the Americans and the Soviet Union to become the first nation to land astronauts on the Moon.

On 31 January 1958, the US successfully launched its first satellite Explorer, but it was decided that a dedicated American national space agency needed to be founded if it was to lead the world in space exploration - and fast.

Naca was already spending about half its time on space-related projects anyway, including the X-15.

So, it was decided that a new agency would be formed off the back of Naca. This would be called the National Aeronautics and Space Administration - or Nasa.

On 29 July 1958, Congress passed the National Aeronautics and Space Act outlining plans for the new organisation - and Nasa became fully operational on 1 October 1958.

On 15 October after Nasa was formed, the X-15 made its first public appearance. The organisation's website explains: "Perhaps of all the X-planes Nasa has been associated with, none was more cutting edge and became more famous than the X-15 rocket plane."

It taught engineers a lot about how to operate aircraft in difficult environments and at high speeds. Three X-15s were flown a total of 199 times between 8 June 1959 and 24 October 1968, travelling at the edge of space at hypersonic speeds.

Unfortunately for the Americans though, disaster struck again in 1961 when the Soviet Union beat them to another milestone and became the first nation to send a man into space. The Soviets were well and truly winning the space race.

So US President John F Kennedy made a pledge to the world that America was going to be the first nation to put an astronaut on the Moon.

On 20 July 1969, Nasa delivered on this promise. Its Apollo 11 mission put man on the Moon for the very first time and several more Apollo missions to the Moon followed in the years to come. They had done it.

There is debate over who truly won the space race. America had been the first nation to put a man on the Moon, but the Soviets hit several important milestones first, including performing the first spacewalk and sending the first man-made object into orbit around the Earth.

Development work on the X-15 plane had a direct impact on the historic Apollo missions, as well as the Mercury programme (to see how well humans could survive spaceflight) and Gemini mission (to take more than one astronaut to space to carry out tasks in space).

It also impacted the space shuttle programme - a reusable spacecraft for travelling to and from orbit around the Earth - which landed for the final time in 2011, so X-planes were a pretty big deal for Nasa.

To this day, Nasa remains one of the world's leading organisations when it comes to space exploration and it continues to invest millions of dollars in researching and developing new aircraft, and exploring the world beyond our atmosphere.

X-planes are still being developed today to test out the latest ideas for amazing new aircraft - whether it's different wing sizes, tail shapes or types of engine.

"They certainly are all interesting in their own way. Each one of them has a unique place in aviation that helps them make their mark in history," explained Nasa's chief historian Bill Barry. "And they are really cool."

One of Nasa's goals at the moment is to develop aircraft that can burn less fuel, cause less pollution and make less noise than the current planes in our skies. It is currently working on QueSST - Quiet Supersonic Technology - to allow us to fly faster than the speed of sound without making a noisy supersonic boom. If everything goes to plan, it is thought it could hit the skies around 2020.

Interestingly, it is only once someone has been chosen to build new aircraft that it is decided whether or not they will be given their own special X number.

Whether it is developing speedy new aircraft or cutting edge probes to explore space, it is safe to say Nasa still has loads more work that it wants to do to explore our skies and beyond.