What Jansky had observed was the 14.6m wavelength radio wave from the Milky Way's core.

There are innumerable stars in the galaxy.

There are many galaxies in the universe.

There are many, many planets in the Milky Way which are just as big as Jupiter.

We live in the Milky Way galaxy.

The universe contains all of the galaxies, stars, and planets.

The size of a galaxy may be as little as a thousand light-years across or as much as a million light-years across.

A galaxy is a cluster of stars, dust, and gas which is held together by gravity.

Hanako's favorite anime is "Night on the Galactic Railroad".

An irregular galaxy has an undefined shape and is full of young stars, dust, and gas.