What is the difference between the galaxy and the Milky Way?

It is a bit like wondering what the difference is between a star and the Sun, but it is interesting to know why

The ancient Greeks called the Milky Way a band of dim light that can be seen south of the sky on the darkest nights.

But it took many years for it to be identified that this path of light was actually many stars, not only that, but they were our neighboring stars, all part of the same galaxy.

Milk trail

Not only the Greeks noticed the presence of the Milky Way in the sky: in Scandinavian mythology it was thought that it marked the way to the Valhalla.

The Aztecs called her Mixcoatl, serpent of the clouds, god of the storms, who crossed the sky in the dark nights.

It was that ghostly appearance of its light, which caused it to be given the name by which we refer to it in Greece, Milky Way, when explaining it as a path of milk spilled by the goddess Hera, when nursing Hercules when he was a baby.

The term galaxy has the same etymology: it means related to milk and it is the name we later gave to the other objects in the universe that are like our Milky Way.

All the stars

The first to observe that this path of light corresponded to stars, many stars, was Galileo Galilei in the 17th century, it was one of the many astronomical discoveries he made with the telescope.

Then, William Herschel, who built the first large optical telescope at the end of the 18th century, made a first map of the stars in the Milky Way and even tried to locate the Sun, although it placed it very close to the center.

For a long time, until the beginning of the 20th century, astronomers thought that the Milky Way contained all the stars in the Universe.

Until in 1920 the observations of Edwin hubble, led to the conclusion that this was just one of many other galaxies.

Galactic neighborhood

That appearance of a scattered path that the Milky Way has, is due to the position of our Solar System in it: in one of its arms, near the shores.

Ours is a spiral galaxy: it is a more or less flat disk of stars, gas and dust, where some of its material is spread out on the edges in formations that we call arms.

Now we know that the Sun is in the arm of Orion, and from here we see a good part of the disk of the galaxy and even its center, where by the way, there is a supermassive black hole.

And perhaps the Greeks or the Aztecs when they looked at the sky did not know that this path of light was the galaxy where they lived, as we do now, but they had an advantage: they could see it better, because there was no artificial lighting.

So if you live far from light pollution or can go somewhere with dark nights, don’t forget to look up at the sky to get a glimpse of our galactic neighborhood.