Out of this
14. and whirl: Whirlpool galaxy
(M51)
companion galaxy
The graceful, winding arms of the majestic spiral galaxy M51 (NGC 5194) appear like a grand spiral staircase sweeping
through space. They are actually long lanes of stars and gas laced with dust.
This sharpest-ever image, taken in January 2005 with the Advanced Camera for Surveys aboard the Hubble Space
Telescope, illustrates a spiral galaxy’s grand design, from its curving spiral arms, where young stars reside, to its yellowish
central core, a home of older stars. The galaxy is nicknamed the Whirlpool because of its swirling structure.
The Whirlpool’s most striking feature is its two curving arms, a hallmark of so-called grand-design spiral galaxies. Many
spiral galaxies possess numerous, loosely shaped arms that make their spiral structure less pronounced. These arms serve
an important purpose in spiral galaxies. They are star-formation factories, compressing hydrogen gas and creating
clusters of new stars. In the Whirlpool, the assembly line begins with the dark clouds of gas on the inner edge, then moves
to bright pink star-forming regions, and ends with the brilliant blue star clusters along the outer edge.
The Whirlpool is one of astronomy’s galactic darlings. Located approximately 25 million light-years away in the
constellation Canes Venatici (the Hunting Dogs), the Whirlpool’s beautiful face-on view and closeness to Earth allow
astronomers to study a classic spiral galaxy’s structure and star-forming processes.
Credit: NASA, ESA, S. Beckwith (STScI), and The Hubble Heritage Team STScI/AURA)