But in some of the spiral arms, humans at last began to hold their own.

A shape to the spiral arms, or perhaps even a color profile.

Until recently, there were thought to be four major spiral arms which all start near the Galaxy's center.

Looking at the crowd that seems to be on the way along the spiral arm, maybe that's a good thing.

You know we're way out in one of the galactic spiral arms.

Ridges cut across both the inside and outside of the spiral arms.

Will they take apart the spiral arm with their rage?

Chief cause of war and turmoil across a dozen spiral arms.

We aren't far, here, from the northern verge of the spiral arm.

At last the whole galactic spiral arm came into view.

It is thought to be the cause of unusual bending in the spiral arms.

They are also very strong and once dominated the spiral arm where humans now live.

We're way out on thin fringe of spiral arm, you remember.

It has very tight spiral arms and a bright core.

It is also a peculiar galaxy because one of its spiral arms goes out more than the other.

The space within them is much clearer than in the spiral arms, almost a perfect vacuum.

To the image on the screen was added a huge curved line that cut a little way into the spiral arm.

One spiral arm may appear to be considerably brighter than the other.

Spiral arms also have the ability to cause climatic changes on a planet.

In pictures of M51 these show up as the bright blue 'knots' throughout the spiral arms.

"Looks like the Spiral Arm has closed down for the season."

"Most of the star formation going on now is happening in the spiral arms.

It is called a "grand design" galaxy because of its well defined spiral arms.

There were periods when whole spiral arms would be abandoned by one civilization or the other.

"Best magician in this whole spiral arm, and two more besides."