A gorgeous spiral galaxy some 100 million light-years distant, NGC 1309 lies on 
the banks of the constellation Eridanus. NGC 1309 spans about 30,000 light-years, 
one third the size of our larger Milky Way galaxy. Bluish clusters of young stars 
and dust lanes are seen to trace out NGC 1309's spiral arms as they wind around 
an older yellowish star population at its core. Not just another pretty face-on 
spiral galaxy, observations of NGC 1309's recent supernova and cepheid stars 
contribute to the calibration of the expansion of the Universe. Still, after you 
get over this beautiful galaxy's grand design, check out the array of more distant 
background galaxies also recorded in the sharp Hubble Space Telescope view.

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Looking like a child's pinwheel ready to be set a spinning by a gentle breeze, 
this dramatic spiral galaxy is one of the latest viewed by NASA's Hubble Space 
Telescope. Stunning details of the face-on spiral galaxy, cataloged as NGC 1309, 
are captured in this color image. Recent observations of the galaxy taken in visible 
and infrared light come together in a colorful depiction of many of the galaxy's 
features. Bright blue areas of star formation pepper the spiral arms, while ruddy 
dust lanes follow the spiral structure into a yellowish central nucleus of 
older-population stars. The image is complemented by myriad far-off background 
galaxies.

However, this galaxy image is more than just a pretty picture. It is helping 
astronomers to more accurately measure the expansion rate of the universe. NGC 1309 
was home to supernova SN 2002fk, whose light reached Earth in September 2002. This 
supernova event, known as a Type Ia, resulted from a white dwarf star accreting 
matter from its companion in a binary star system. When the white dwarf collected 
enough mass and was no longer able to support itself, the star detonated, becoming 
the brightest object in the galaxy for several weeks.

Nearby type Ia supernovae like SN 2002fk in NGC 1309 are used by astronomers to 
calibrate distance measures in the universe. By comparing nearby type Ia supernovae 
to more distant ones, they can determine not only that the universe is expanding, 
but that this expansion is accelerating. However, this method only works if the 
distance to the host galaxies is known extremely well.