how many miles is the outside of the milky way?

Answer 1

Firstly- 'miles' aren't the useful unit of measure here- they're far too small.

While the galaxy is 100,000 light years in diameter- you don't need to travel 100,000 light years in order to leave it. It's fairly flat- like a record er... uh.. .I mean CD. Plus- we're about 2/3'rds of the way out on an arm. So- you can leave in the plane of the galaxy and be pretty much outside of it in 20,000 light years. Or- go out normal to (perpendicular to) the plane, and be out in about 5,000 light years.

Answer 2

The above answers are right in their own fashion, but they all depend on how you define "outside" the milky way. How do you define that? One scale height of the stellar disk? Beyond the furthest object (think globular cluster) that is gravitationally bound specifically to the Milky Way and not to the Local Group of galaxies in general? Some "cliff" in the radial star formation rate function as you move out from the galactic center?

Answer 3

As the Mily Way is 100,000 light years in diameter, the circumference is about 314,159 light years. Now convert light years into miles and multiply.

Answer 4

well

our galaxy is estimated at 80'000 to 100'000 light-years in diameter

if it is perfectly circular (it must be very close in any case because of symmetry) then its perimeter must be 251'000 to 314'000 light years.

a light year is the distance covered by light in a year, i.e. 5.87E12 miles (at 186'000 miles per second).

so this would give you, for our galaxy, the Milky Way, a perimeter between 1.48E18 and 1.84E18 miles, i.e. between 1.45 and 1.84 billion billion miles.


hope this helps