It's impossible to give a precise number for how long it takes light to travel across the Milky Way because:

* The Milky Way is not perfectly shaped: It's a spiral galaxy with a central bulge, a disk, and a halo.

* The Milky Way is vast: Estimates vary, but it's about 100,000 light-years across.

* Light doesn't travel in a straight line: It can be affected by gravity and other factors, making its path unpredictable.

However, we can make some estimations. If we consider the diameter of the Milky Way to be approximately 100,000 light-years, it would take light about 100,000 years to travel across it.

This is a long time, highlighting the immense scale of our galaxy.