Question

How far are other galaxies from earth?

Answer 1

Between `25 xx 10^3` light years (nearest) and `13.3 xx 10^9` light years (farthest)

Explanation:

The nearest would be a satellite galaxy of the Milky Way.

There seem to be two possible candidates:

(1) Canis Major Dwarf Galaxy / Canis Major Overdensity.

This is a disputed dwarf irregular galaxy about `25`kly (thousand light years) from Earth.

(2) Saggitarius Dwarf Spheroidal/Elliptical Galaxy about `70`kly from Earth.

The nearest major galaxy is the Andromeda Galaxy M31, situated about `2.5`Mly (million light years) from Earth. At about `220`kly in diameter, it is definitely larger than the Milky Way galaxy.

The third largest spiral galaxy in the Local Group is the Triangulum Galaxy at a distance estimated to be somewhere between `2.38`Mly and `3.07`Mly, with a diameter of about `60`kly.

The most distant known galaxy is MACS0647-JD at a distance of `13.3`Bly (billion light years), meaning that we see it as it was about `420` million years after the Big Bang.

Given that a light year is about `5.8785 xx 10^12` miles, that means that our nearest neighbouring galaxy is about `1.5 xx 10^17` miles (Canis Major Dwarf Galaxy) or `4 xx 10^17` miles (Saggitarius Dwarf Spheroidal Galaxy) away and the most distant known galaxy is `7.8 xx 10^22` miles away.

Actually the (comoving) distance to the farthest galaxy is considerably more than this due to the expansion of the universe, probably closer to `44.8 xx 10^9` ly or `2.6 xx 10^23` miles.