Just like the Earth orbits the Sun in our Solar System, our Solar System orbits the Milky Way, the galaxy we call home.
Our Solar System completes a revolution around the galaxy every 250 millions years. This corresponds to when dinosaurs were just beginning to come into existence.
NASA scientist Jessie Christiansen was inspired to create the comparison after making a passing comment about the last time our planet was at its current position in the galaxy while leading a stargazing party. Her work illustrates how long dinosaurs roamed the Earth and the relatively short time humans have been around.
Something else to consider: the Milky Way is also moving through space.
Bringing this into the realm of fiction, this could be a fascinating fact to investigate during time travel. Everyone assumes that during time travel, the traveler stays stationary. This only works if this logic is applied to the same point on Earth. If they were to truly travel through space they would end up in a vacuum, or on another planet if they were lucky. Giving it more thought, although it would be highly unlikely, this could provide the traveler with a way to come into contact with an alien civilization on another planet, existing at another time.
The fact that the Milky Way is in fact moving also would allow for the time traveler to appear in another galaxy altogether, making civilization’s ability to navigate between the stars not entirely necessary.
The story could revolve around either 1) a traveler who doesn't know and who lucks into a new planet (or dies in the vacuum of space) or 2) a traveler who accounts for the shifting planets and uses the knowledge to investigate far into the past or future, hopping onto the exact same spot but traveling great distances.
