MILKY WAY GALAXY vs OBSERVABLE UNIVERSE

The observable Universe is 93 billion light-years, yet, our galaxy, the Milky Way, is just 100,000 light-years in diameter. It would take us endless generations just to explore our galaxy, let alone the Universe.

Assuming a factor of roughly 600,000 between the size of the Milky Way (150,000 ly) and the estimated size of the observable universe (93 bn ly), as well as the size of a Euro coin of 23.25 mm (just short of an inch), we can calculate:

23.25⋅600000=13950000$23.25\cdot 600000=13950000$

Turning millimetres into metres we get:

139500001000≈14000$\frac{13950000}{1000}\approx 14000$

So, with the galaxy being the size of a Euro coin the observable universe would be 14 km (8.7 miles) in diameter, a distance corresponding to a 2½-3 hours walk or an 8–9 minute drive on the freeway.