NASA (Hubble Space Telescope) Study of Barred Spirals

Bars form when stellar orbits in a spiral galaxy become unstable and deviate from a circular path. The tiny elongations in the stars' orbits grow and they get locked into place, making a bar.

NASA study with Hubble Space Telescope found barred spiral galaxies were far less plentiful 7 billion years ago than they are today, in the local universe.

Only 20 percent of the spiral galaxies in the distant past possessed bars, compared with nearly 70 percent of their modern counterparts.

Bars have been forming steadily over the last 7 billion years, more than tripling in number.

Our Milky Way Galaxy, another massive barred spiral, has a central bar that probably formed somewhat early, like the bars in other large galaxies in the Hubble survey.

Understanding how bars formed in the most distant galaxies will eventually shed light on how it occurred here, in our own backyard.

Read more here.