1.   Blue represents the main galactic structure of spiral arms composed of young and middle-aged stars.

2.   In most cases, astronomers said, red knots in the spiral arms pinpointed rich star-forming regions.

3.   Light shining through the slit was to be analyzed spectroscopically to reveal the chemical composition and motion of the spiral arm.

4.   Moreover, Gonzalez suggested, the habitable zone was unlikely to include the densely packed spiral arms of the galaxy.

5.   The idea was to align a narrow slit in the telescope with one spiral arm of a galaxy many millions of light-years away.

6.   This is true from the double helix of DNA through the knobbly whorls on a pine cone and up through the spiral arms of a galactic nebula.