A British-built satellite has blasted into orbit from Kazhakstan, marking the start of Europe's own satellite navigation system called Galileo.
Giove-A is the first of a network of satellites which will rival the US's Global Positioning System - or GPS.
It will be used to tell you exactly where you are at any time, and could be put into mobile phones to help you find the nearest cinema, or sports centre.
Scientists plan to launch a total of 30 satellites over the next five years.
The 600kg spacecraft was lifted into orbit on a Soyuz rocket at 5.19am on Wednesday.
Once the Galileo system is fully up and running it will be used to guide cars through satellite navigation systems - which is a bit like a computerised map which gives you directions.
At the moment cars use the US GPS system, but it's hoped the new European version will be even more accurate.
And it could also be used to help aeroplane pilots work out their flight paths.