One of the dust lanes of M51 appears to be drawn into it or is superimposed upon it as the two galaxies are passing each other. The mottled appearance in the arm of the Whirlpool closest to NGC 5195 has been caused by new star generation. As the two galaxies have been passing each other, turbulence has caused a burst of star-forming activity in these regions. Orbiting the center of our galaxy like a miniature galaxy in itself, globular clusters can contain up to a million stars. M13, about 22,000 light years distant from the sun, is one of the best examples of such a stellar system.
Globular clusters are older aggregates of stars, formed early in the history of galaxies.
They are composed of stars like our sun or stars which have less mass than the sun. Gravity keeps the clusters intact. Stellar densities are as high as 100 stars per cubic light year at the centers of these systems. The pillars themselves are dust clouds immersed in a glowing cloud of luminous hydrogen gas. They are stellar nurseries.