The Crab Nebula wasn't "seen" on Earth in 1054, it was *observed* on Earth. And it wasn't a physical object traveling to Earth, but rather a supernova explosion that *became* visible on Earth in 1054.

Here's the breakdown:

* Supernova: The Crab Nebula is the remnant of a massive star that exploded as a supernova.

* Distance: This supernova occurred approximately 6,500 light-years away.

* Light Travel Time: Since light travels at a finite speed, it takes time for light from an event to reach us. In this case, the light from the Crab Nebula's supernova took approximately 6,500 years to reach Earth.

Therefore, the light from the Crab Nebula's supernova explosion that was observed in 1054 AD actually occurred around 6,500 years BC!