We Are Inside the Picture

The Milky Way is the galaxy in which our solar system is. That is, when you look at it, you are looking at the house from the inside.

And that explains the shape you see. A spiral galaxy is a flat plate: the diameter of ours is about 100,000 light years, and its thickness only about 1,000 light years. We sit inside this plate, not above it. And so, when you look along the plate, you see a great many stars packed together — a band. And when you look out of it, up or down, you see far fewer.

That band is what is seen on dark, clear nights: a kind of whitish, hazy path, and from it comes the name.

And the shape of our galaxy is not a simple spiral. It is a barred spiral galaxy: at its center is an elongated structure of stars, and from its ends the arms come out. And in Hebrew it was also called in the past 'the milky valley' and 'the milky path', and in both names you hear the same thing — people saw a white band in the sky and tried to describe it in words.

And how many stars are there? Between 100 billion and 400 billion. The number is not exact, and not by accident — you cannot count from the inside.

And a light year is not a unit of time. It is the distance light travels in a year, and light is the fastest thing there is. A galaxy 100,000 light years wide means that light that set out from one end of it arrives at the other end after 100,000 years.

And where are we inside it? At a distance of about 26,000 light years from the center of the galaxy, on an arm called the Orion Arm. Not at the center. Halfway out, on one of the arms.

And one more thing, and it is surprising. All the stars that can be seen from the earth with the naked eye — about 6,000 in areas without light pollution — all belong to the Milky Way. That is, everything that is seen in the sky at night, without a telescope, is inside our galaxy.

And that makes the whitish band into something entirely different. It is not one more object in the sky. It is all the rest of the place we are inside, too far away for us to separate the stars in it.

And in the Negev, on a dark night, you see it. That is not self-evident, and most people in the world can no longer see it at all.