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In
1995, Hubble observed this majestic spiral galaxy,
known as NGC 4414, as part of a key astronomical
mission to accurately determine distances of many
galaxies from Earth. The key was to find stars
that vary in brightness. Called Cepheids, astronomers
use these stars as standard distance indicators.
Knowing distances allows astronomers to more accurately
determine the universe's rate of expansion. This
value is used to calculate distances, sizes, and
the luminosity of other objects in the universe,
as well as the age of the universe itself. However,
the observation was incomplete. Given the galaxy's
very large size, Hubble could only view half the
galaxy, requiring a return visit to capture the
other half. In 1999, the telescope did just that,
producing this stunning, full-color portrait.
The new image shows that the central region of
the galaxy is typical of most spiral-shaped galaxies:
it contains mostly yellow and red stars, an indication
that they are much older than the blue-colored
stars residing in the galaxy's spiral arms. The
arms also are rich in interstellar dust, which
is seen as dark patches and streaks silhouetted
against the starlight.
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