100
If you could travel as fast as the speed of light (186,282 miles a second) it would take you 100,000 years to cross me.
What is The Milky Way Galaxy. (Creation Book page 117 par. 6)
How many miles is that? Well, since light travels about six trillion miles in a year, multiply that by 100,000 and you have the answer: our Milky Way galaxy is about 600 quadrillion (600,000,000,000,000,000) miles in diameter.