# What is the diameter of the universe?

##### 1 Answer

It is better to address universe as our universe or observable universe. Our galaxy Milky Way (MW) diameter is about 3.3 billion AU. The dimensions beyond MW are undefined.

#### Explanation:

Universe as

As of now, it is reasonable to confine ourselves to our galaxy Milky Way, for estimating distances.

We are at 25000 - 27000 light years, from the center of Milky Way. So, its 2-significant digits (sd) diameter, in AU, is 2 X 2,6 E+04 X 6.3 E+04 AU = 3.3 billion AU.

1 ly = 62900 AU, nearly.

International astronomical Union (IAU) definition AU = the mathematical average of Sun-Earth distance = semi-minor axis b of the Earth's elliptic orbit (in 10-sd) = 149597670.7 km.

As of now, the precision is getting lesser for stars and galaxies.it is It