What did you dream of being when you were younger? A fireman? A ballerina? Maybe a dinosaur?
For children in Hertfordshire with hopes of being an astronaut, that dream may now seem a little more achievable.
That's because they had a visit from the first British man to ever walk in space - Tim Peake - as he opened a new centre aiming to make young people passionate about science.
ITV News Anglia's Russell Hookey was there too - you can watch his video report above.