Photo of the core of the Milky Way (above)

A Galactic year is the time that it takes our planet Earth to orbit around the center of the Milky Way Galaxy. Not only does a Galactic year describe the amount of time it takes Earth but it tells us the time of orbit for our whole solar system. Even though our solar system may seem gigantic to us, it only makes up a very very small fraction of the Milky Way Galaxy.

The best estimates describe a galactic year as taking 225 million to 250 million Earth years to complete one orbit. The Milky Way Galaxy is roughly 4.5 billion years old so that means our solar system is about 20 Galactic years old. It is thought that we are traveling at an average of 250 km/sec around the center of the galaxy!